Resist polymer and resist composition

ABSTRACT

The resist polymer of the present invention comprises a specific constitutional unit having a cyano group, a constitutional unit having an acid-dissociable group, and a specific constitutional unit having a lactone skeleton. When the above polymer is used as a resist resin in DUV excimer laser lithography or electron beam lithography, it exhibits high sensitivity and high resolution, and provides a good resist pattern shape, having a small degree of occurrence of line edge roughness or generation of microgels.

TECHNICAL FIELD

The present invention relates to a resist polymer and a resistcomposition. In particular, the present invention relates to achemically amplified resist composition, which is preferably used infine processing using an excimer laser or electron beam.

BACKGROUND ART

In recent years, a minimization has quickly progressed as a result ofthe development of lithographic techniques in the field of fineprocessing for production of semiconductor devices or liquid crystaldevices. As such means for the minimization, the wavelength of anirradiation light has generally been shortened. Specifically, such anirradiation light has been changed from the conventional ultraviolet rayincluding g-line (wavelength: 438 nm) and i-line (wavelength: 365 nm) astypical examples, to DUV (deep ultra violet).

Presently, a KrF excimer laser (wavelength: 248 nm) lithographictechnique has been introduced into the market, and an ArF excimer laser(wavelength: 193 nm) lithographic technique, which is directed towardsthe further shortening wavelength of an irradiation light, is beingintroduced. Moreover, an F₂ excimer laser (wavelength: 157 nm)lithographic technique is being studied as a technique for the nextgeneration. Furthermore, an electron beam lithographic technique, whichsomewhat differs from the above techniques, is also intensively beingstudied.

As a resist with high resolution for such an irradiation light with ashort wavelength or electron beam, a “chemically amplified resist”containing a photoacid generator has been proposed. At present, theimprovement and development of this chemically amplified resist havevigorously been progressing.

In accordance with the shortening wavelength of an irradiation light,the structure of a resin used for resists has also changed. For example,in the KrF excimer laser lithography, polyhydroxystyrene having hightransparency to an irradiation light with a wavelength of 248 nm ormodified resins in which hydroxyl groups in polyhydroxystyrene areprotected with an acid-dissociable solubility-inhibiting group are used.However, in the ArF excimer laser lithography, the above resins cannotalways be used because their transparency is insufficient to the laserwith a wavelength of 193 nm.

Accordingly, as a resist resin used in the ArF excimer laserlithography, an acrylic resin that is transparent to a laser with awavelength of 193 nm has become a focus of attention. As such an acrylicresin, a copolymer of (meth)acrylic acid ester having an adamantaneskeleton at an ester moiety thereof and (meth)acrylic acid ester havinga lactone skeleton at an ester moiety thereof is disclosed in JapanesePatent Laid-Open Nos. 10-319595, 10-274852, or the like.

However, when these acrylic resins are used as resist resins, resistpatterns to be formed are not necessarily favorable. Thus, the crosssection of a resist pattern shape formed by using such an acrylic resinbecomes a convex or concave form and therefore, precise lithography ontoa substrate to be processed cannot be performed in some cases. Moreover,when the resin contained in a resist composition condenses with time,the insoluble matter called a microgel generates. Thus, voids generatein a resist pattern, and as a result, disconnection or defect may occurin a circuit.

Recently, in the production of semiconductor devices, the diameter of asubstrate has grown from 200 mm to 300 mm. However, in the case of usingsuch a large substrate, the size of a resist pattern to be formed islikely to vary.

In the production line of semiconductor elements, baking such as PEB(post exposure baking) is carried out. A difference (approximatelyseveral degrees (° C.)) in the heat treatment temperature (PEBtemperature) may be generated among baking units (baking devices). As aresult, there are some cases where, due to such a difference in thetemperature, the size of a resist pattern to be formed is differentdepending on a baking unit that is used. Accordingly, a resist patternthat does not significantly depend on the PEB temperature has beendesired.

On the other hand, a chemically amplified resist composition, whichcomprises a resin containing a constitutional unit having a cyano group,is disclosed in Japanese Patent Laid-Open Nos. 2002-244295, 2000-258915,2002-268222, and 2001-264982, for example. Japanese Patent Laid-Open No.2002-244295 describes a cyano group as a substituent of an alicyclichydrocarbon group contained in a group that is dissociated by the actionof acid contained in a resin (acid-dissociable group). Japanese PatentLaid-Open No. 2000-258915 describes that a cyano group havingpolymerization unit maintains its adhesiveness to a substrate due to thepresence of a cyano group as a polar substituent, thereby contributingto the improvement of the dry etching resistance of a resist. JapanesePatent Laid-Open No. 2002-268222 describes that the use of a resincontaining a specific constitutional unit having a cyano group enablesthe improvement of line edge roughness. Japanese Patent Laid-Open No.2001-264982 describes that the use of a resin containing a specificconstitutional unit having a cyano group enables the improvement oftransparency to 157 nm that is an F₂ excimer laser wavelength.

However, resist compositions, which comprise the resins containing aconstitutional unit having a cyano group described in the aforementionedpublications, cannot sufficiently inhibit roughness on the side wall ofa resist pattern that is generated as a result of the patterning with anexcimer laser and the subsequent processing procedure, that is, thegeneration of line edge roughness. Accordingly, in order to achievefurther line slimming, a circuit width might become uneven or thecircuit might be broken down, and there may be a risk of resulting indecrease in a yield during the production process of semiconductors.

As an acrylic monomer that will be a material for a polymer that isuseful as an optical material having excellent optical properties, lowhygroscopicity, and heat resistance, Japanese Patent Laid-Open No.1-100145 discloses an ester derivative of a (meth)acrylic acid having analicyclic skeleton with a cyano group as a substituent. In addition,Japanese Patent Laid-Open No. 1-100145 describes that the above esterderivative of a (meth)acrylic acid can be used singly or in the form ofa copolymer of itself and other unsaturated compounds such as(meth)acrylic acid or an ester thereof.

Moreover, Japanese Patent Laid-Open No. 2-193958 discloses a methacrylicacid ester having an alicyclic skeleton with a cyano group as asubstituent. Japanese Patent Laid-Open No. 2-189313 discloses athermoplastic resin formed by polymerization of a monomer compositioncontaining a methacrylic acid ester that includes those described in theaforementioned Japanese Patent Laid-Open No. 2-193958, or a monomercomposition containing a methacrylic acid ester and (meth)acrylic acidester that includes those described in the aforementioned JapanesePatent Laid-Open No. 2-193958. Moreover, Japanese Patent Laid-Open No.2-189313 describes that the above thermoplastic resin is excellent interms of heat resistance, transparency and anti-hygroscopicity, and isuseful for an adhesive, a paint, a fiber-treating agent, amold-releasing agent, a resin-modifier, a selectively permeablemembrane, etc.

Furthermore, Japanese Patent Laid-Open No. 2-216632 describes that apolymer comprising a constitutional unit having a cyano group is usefulfor an optical disk substrate. Still further, Japanese Patent Laid-OpenNo. 2-211401 describes that a polymer comprising a constitutional unithaving a cyano group is useful for optical components and opticalelements. Still further, Japanese Patent Laid-Open No. 1-92206 describesthat a polymer comprising a constitutional unit having a cyano group isuseful as a material for an optical disk, plastic lens, or the like.

Still further, U.S. Pat. No. 6,165,678 describes a resist composition,which comprises a (meth)acrylic copolymer comprising a constitutionalunit having a group having a polar moiety and a constitutional unithaving a group that is dissociated by the action of acid, and aphotoacid generator. This publication describes that the above resistcomposition is excellent in terms of sensitivity and resolution, andthus that it is used in ArF excimer laser (wavelength: 193 nm)lithography or the like. In this publication, examples of a polar moiety(polar group) may include a cyano group and lactone. In addition, theexamples section in the aforementioned U.S. Pat. No. 6,165,678 describesa polymer formed by polymerization of pantolactone methacrylate,isobornyl methacrylate, and methacrylic acid (Example 3), a polymerformed by polymerization of 5-(4-)cyano-2-norbornyl methacrylate,2′-acetoxyethyl methacrylate, 1-butyl methacrylate, and methacrylic acid(Example 4), a polymer formed by polymerization of5-(4-)cyano-2-norbornyl methacrylate, methacrylonitrile, t-butylmethacrylate, and methacrylic acid (Example 5), and a polymer formed bypolymerization of 5-(4-)cyano-2-norbornyl methacrylate, t-butylmethacrylate, and methacrylic acid (Example 6).

However, the aforementioned U.S. Pat. No. 6,165,678 does not describe aresist polymer, which comprises a constitutional unit having a cyanogroup, a constitutional unit having an acid-dissociable group, and aconstitutional unit having a lactone skeleton. With regard to the resistcomposition described in the example section of the aforementioned U.S.Pat. No. 6,165,678, it cannot necessarily be said that a resist patternshape to be formed is favorable, and that the occurrence of line edgeroughness and generation of microgels are less degree.

Japanese Patent Laid-Open No. 11-352694 discloses a chemically amplifiedresist material, which comprises: an acid-sensitive polymer, which has aconstitutional unit containing an alkali-soluble group protected by aprotecting group having a moiety containing at least one nitrile grouphaving self-dissociable ability, wherein the above alkali-soluble groupis dissociated due to acid, so as to impart alkali solubility to theabove copolymer, a constitutional unit containing an alkali-solublegroup protected by a protecting group having alicyclic hydrocarbon,wherein the above alkali-soluble group is dissociated due to acid, so asto impart alkali solubility to the above copolymer, and a constitutionalunit containing an alkali-soluble group protected by a protecting grouphaving a lactone structure, wherein the above alkali-soluble group isdissociated due to acid, so as to impart alkali solubility to the abovecopolymer; and an acid generator. The example section of Japanese PatentLaid-Open No. 11-352694 describes polymers containing2-methyl-1-propionitrilecyclohexyl methacrylate as a constitutional unithaving a cyano group (Examples 4, 5, 6, and 7), and a polymer containing2-ethyl-1-propionitrilecyclohexyl methacrylate as a constitutional unithaving a cyano group (Example 8).

However, the polymers described in the examples in the aforementionedJapanese Patent Laid-Open No. 11-352694 are not necessarily sufficientin terms of the stability of a constitutional unit having a cyano group.Thus, when these polymers are used as resist resins, the physicalproperties thereof may change in some cases, and it may be difficult tohandle such polymers. In addition, the resist composition described inthe examples in the aforementioned Japanese Patent Laid-Open No.11-352694 is not necessarily sufficient in terms of dry etchingresistance.

Japanese Patent Laid-Open No. 2003-122007, published on Apr. 25, 2003,discloses a positive-acting resist composition, which comprises a resincontaining a constitutional unit having a cyano group, a constitutionalunit having an alicyclic lactone structure and a constitutional unithaving an alicyclic hydrocarbon group, and a photoacid generator.Japanese Patent Laid-Open No. 2003-122007 describes constitutional unitshaving cyclohexane lactone, norbornane lactone, or adamantane lactone,as constitutional units having an alicyclic lactone structure. Morespecific examples are given below.

Moreover, the aforementioned Japanese Patent Laid-Open No. 2003-122007describes that the resin used for the resist composition may alsocomprise a constitutional unit having a lactone structure. Specificexamples of such a constitutional unit having a lactone structure aregiven below.

However, the resist composition described in the aforementioned JapanesePatent Laid-Open No. 2003-122007, which comprises a constitutional unithaving cyclohexane lactone or norbornane lactone as a constitutionalunit having an alicyclic lactone structure, a constitutional unit havinga cyano group, and a constitutional unit having an alicyclic hydrocarbongroup, is not necessarily sufficiently be favorable in terms of a resistpattern shape formed therefrom. Moreover, a polymer comprising aconstitutional unit having adamantane lactone as a constitutional unithaving an alicyclic lactone structure, a constitutional unit having acyano group, and a constitutional unit having an alicyclic hydrocarbongroup, is generally expensive, and such a polymer is not always beexcellent in terms of solubility in organic solvents.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide: a resist polymer,which exhibits high sensitivity and high resolution, and can provide agood resist pattern shape, having a small degree of occurrence of lineedge roughness or generation of microgels, when it is used as a resistresin in DUV excimer laser lithography or electron beam lithography; aresist composition; and a method of forming a pattern using the aboveresist composition.

Another object of the present invention is to provide: a resist polymer,which achieves a uniform resist pattern size in plane on a substrate,even when a large substrate with a diameter of 300 mm or greater isused; a resist composition; and a method of forming a pattern using theabove resist composition.

The present invention relates to a resist polymer, which comprises aconstitutional unit represented by formula (1) indicated below, aconstitutional unit having an acid-dissociable group, and aconstitutional unit having a lactone skeleton that is represented by atleast one selected from the group consisting of formulas (4-1), (4-2),(4-3), (4-5), (4-6), and (4-10) indicated below:

(wherein, in formula (1), R⁰¹ represents a hydrogen atom or a methylgroup; R⁰² represents a hydrogen atom or an alkyl group having 1 to 4carbon atoms; Z represents an atomic group that constitutes a cyclichydrocarbon group together with a carbon atom constituting an ester bondand a carbon atom to which cyano group binds; and p represents aninteger between 1 and 4,

provided that when p is 2 or greater, cyano groups may bind to a singlecarbon atom or may bind to different carbon atoms,)

(wherein, in formula (4-1), R⁴¹ represents a hydrogen atom or a methylgroup; each of R⁴⁰¹ and R⁴⁰² independently represents a hydrogen atom, alinear or branched alkyl group having 1 to 6 carbon atoms, a hydroxygroup, a carboxy group, or a carboxy group that is esterified withalcohol having 1 to 6 carbon atoms, or R⁴⁰¹ and R⁴⁰² together represent—O—, —S—, —NH—, or a methylene chain having 1 to 6 carbon atoms{—(CH₂)_(j)— (wherein j represents an integer between 1 and 6)}; irepresents 0 or 1; X⁵ represents a linear or branched alkyl group having1 to 6 carbon atoms that may have, as a substituent, at least oneselected from the group consisting of a hydroxy group, a carboxy group,an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6carbon atoms, a carboxy group that is esterified with alcohol having 1to 6 carbon atoms, a cyano group, and an amino group, a hydroxy group, acarboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy grouphaving 1 to 6 carbon atoms, a carboxy group that is esterified withalcohol having 1 to 6 carbon atoms, or an amino group; and n5 representsan integer between 0 and 4, and m represents 1 or 2, provided that whenn5 is 2 or greater, X⁵ may be a plurality of different groups,

wherein, in formula (4-2), R⁴² represents a hydrogen atom or a methylgroup; each of R²⁰¹ and R²⁰² independently represents a hydrogen atom, alinear or branched alkyl group having 1 to 6 carbon atoms, a hydroxygroup, a carboxy group, or a carboxy group esterified with alcoholhaving 1 to 6 carbon atoms; A¹ and A² together represent —O—, —S—, —NH—,or a methylene chain having 1 to 6 carbon atoms {—(CH₂)_(k)— (wherein krepresents an integer between 1 and 6)}; X⁶ represents a linear orbranched alkyl group having 1 to 6 carbon atoms that may have, as asubstituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, a cyano group,and an amino group, a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, or an amino group; and n6 represents an integer between 0 and 4,provided that when n6 is 2 or greater, X⁶ may be a plurality ofdifferent groups,

wherein, in formula (4-3), R⁴³ represents a hydrogen atom or a methylgroup; each of R²⁰³ and R²⁰⁴ independently represents a hydrogen atom, alinear or branched alkyl group having 1 to 6 carbon atoms, a hydroxygroup, a carboxy group, or a carboxy group esterified with alcoholhaving 1 to 6 carbon atoms; each of A³ and A⁴ independently represents ahydrogen atom, a linear or branched alkyl group having 1 to 6 carbonatoms, a hydroxy group, a carboxy group, or a carboxy group that isesterified with alcohol having 1 to 6 carbon atoms, or A³ and A⁴together represent —O—, —S—, —NH—, or a methylene chain having 1 to 6carbon atoms {—(CH₂)_(l)— (wherein l represents an integer between 1 and6)}; X⁷ represents a linear or branched alkyl group having 1 to 6 carbonatoms that may have, as a substituent, at least one selected from thegroup consisting of a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, a cyano group, and an amino group, a hydroxy group, a carboxygroup, an acyl group having 1 to 6 carbon atoms, an alkoxy group having1 to 6 carbon atoms, a carboxy group that is esterified with alcoholhaving 1 to 6 carbon atoms, or an amino group; and n7 represents aninteger between 0 and 4, provided that when n7 is 2 or greater, X⁷ maybe a plurality of different groups,

wherein, in formula (4-5), R⁴⁵ represents a hydrogen atom or a methylgroup; each of R⁸ and R⁹ independently represents a hydrogen atom or alinear or branched alkyl group having 1 to 8 carbon atoms; each of R⁵²,R⁶², and R⁷² independently represents a hydrogen atom or a methyl group;each of Y¹², Y²², and Y³² independently represents —CH₂— or —CO—O—, andat least one of them represents —CO—O—; X⁹ represents a linear orbranched alkyl group having 1 to 6 carbon atoms that may have, as asubstituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, a cyano group,and an amino group, a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, or an amino group; and n9 represents an integer between 0 and 4,provided that when n9 is 2 or greater, X⁹ may be a plurality ofdifferent groups,

wherein, in formula (4-6), R⁴⁶ represents a hydrogen atom or a methylgroup; R¹⁰ represents a hydrogen atom or a linear or branched alkylgroup having 1 to 8 carbon atoms; each of R⁵³, R⁶³, and R⁷³independently represents a hydrogen atom or a methyl group; each of Y¹³,Y²³, and Y³³ independently represents —CH₂— or —CO—O—, and at least oneof them represents —CO—O—; X¹⁰ represents a linear or branched alkylgroup having 1 to 6 carbon atoms that may have, as a substituent, atleast one selected from the group consisting of a hydroxy group, acarboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy grouphaving 1 to 6 carbon atoms, a carboxy group that is esterified withalcohol having 1 to 6 carbon atoms, a cyano group, and an amino group, ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, or an aminogroup; and n10 represents an integer between 0 and 4, provided that whenn10 is 2 or greater, X¹⁰ may be a plurality of different groups, and

wherein, in formula (4-10), each of R⁹¹, R⁹², R⁹³, and R⁹⁴ independentlyrepresents a hydrogen atom, a linear or branched alkyl group having 1 to6 carbon atoms, a hydroxy group, a carboxy group, or a carboxy groupthat is esterified with alcohol having 1 to 6 carbon atoms, or R⁹¹ andR⁹² together represent —O—, —S—, —NH—, or a methylene chain having 1 to6 carbon atoms {—(CH₂)_(t)— (wherein t represents an integer between 1and 6)}; and m1 represents 1 or 2.)

It is to be noted that, in formulas (4-1), (4-2), (4-3), (4-5), and(4-6), positions substituted with X⁵, X⁶, X⁷, X⁹, and X¹⁰ may be anypositions in the cyclic structures.

In this polymer, constitutional units represented by formula (1) are notnecessarily all the same, but may be a mixture of two or more kindsthereof. Also, constitutional units having an acid-dissociable group arenot necessarily all the same, but may be a mixture of two or more kindsthereof. Also, constitutional units having a lactone skeleton are notnecessarily all the same, but may be a mixture of two or more kindsthereof. That is to say, constitutional units (4-1), (4-2), (4-3),(4-5), (4-6), and (4-10) are not necessarily all the same, respectively,but they may be a mixture of two or more kinds thereof.

In addition, in this polymer, each constitutional unit may have anygiven sequence. Accordingly, this polymer may be a random copolymer, analternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein, in the above-described formula (1), R⁰² represents a hydrogenatom.

The present invention relates to the above-described resist polymer,wherein, in the above-described formula (1), Z represents an atomicgroup that constitutes a bridged cyclic hydrocarbon group together witha carbon atom constituting an ester bond and a carbon atom to which acyano group binds.

The present invention relates to the above-described resist polymer,wherein, in the above-described formula (1), R⁰² represents a hydrogenatom; Z represents an atomic group that constitutes a bridged cyclichydrocarbon group together with a carbon atom constituting an ester bondand a carbon atom to which a cyano group binds, and p is 1.

The present invention relates to the above-described resist polymer,wherein the above-described cyclic hydrocarbon group has a skeletonselected from the group consisting of a cyclic terpene hydrocarbon, anadamantane ring, a tetracyclododecane ring, a dicylclopentane ring, anda tricyclodecane ring.

The present invention relates to the above-described resist polymer,wherein the above-described cyclic hydrocarbon group has a norbornanering.

The present invention relates to the above-described resist polymer,wherein the constitutional unit represented by the above-describedformula (1) is a constitutional unit represented by the followingformula (2):

(wherein, in formula (2), R⁰¹ represents a hydrogen atom or a methylgroup.)

It is to be noted that, in this polymer, the constitutional unitrepresented by formula (2) is not necessarily all the same, but may be amixture of two or more kinds thereof.

The present invention relates to the above-described resist polymer,wherein the constitutional unit represented by the above-describedformula (1) is a constitutional unit represented by the followingformula (1-1):

(wherein, in formula (1-1), R⁰¹ represents a hydrogen atom or a methylgroup; R⁰³ represents a hydrogen atom or a linear or branched alkylgroup having 1 to 6 carbon atoms; and each of A⁰¹ and A⁰² independentlyrepresents a hydrogen atom, or a linear or branched alkyl group having 1to 4 carbon atoms, or A⁰¹ and A⁰² together represent —O—, —S—, —NH—, oran alkylene chain having 1 to 6 carbon atoms.)

It is to be noted that, in this polymer, the constitutional unitrepresented by formula (1-1) is not necessarily all the same, but may bea mixture of two or more kinds thereof.

The present invention relates to the above-described resist polymer,wherein, in the above-described formula (1), p is 1, and a cyano groupbinds to a carbon atom that is adjacent to the carbon atom constitutingan ester bond.

The present invention relates to the above-described resist polymer,wherein the constitutional unit represented by the above-describedformula (1) is a constitutional unit represented by the followingformula (1-2):

(wherein, in formula (1-2), R⁰¹ represents a hydrogen atom or a methylgroup; each of R⁰⁴, R⁰⁵, R⁰⁶, and R⁰⁷ independently represents ahydrogen atom or a linear or branched alkyl group having 1 to 4 carbonatoms, or two out of R⁰⁴, R⁰⁵, R⁰⁶, and R⁰⁷ together represent analkylene chain having 1 to 6 carbon atoms.)

It is to be noted that, in this polymer, the constitutional unitrepresented by formula (1-2) is not necessarily all the same, but may bea mixture of two or more kinds thereof.

The present invention relates to the above-described resist polymer,wherein the above-described constitutional unit having a lactoneskeleton is at least one selected from the group consisting of thoserepresented by the above-described formulas (4-1), (4-2), (4-3), and(4-10).

It is to be noted that, in this polymer, constitutional unitsrepresented by formulas (4-1), (4-2), (4-3), and (4-10) are notnecessarily all the same, respectively, but may be a mixture of two ormore kinds thereof.

The present invention relates to the above-described resist polymer,wherein the total ratio of the constitutional unit represented by theabove-described formula (1) is between 5% and 30% by mole, the totalratio of the constitutional unit having an acid-dissociable group isbetween 30% and 60% by mole, and the total ratio of the constitutionalunit having a lactone skeleton is between 30% and 60% by mole.

The present invention relates to the above-described resist polymer,wherein the above-described constitutional unit having anacid-dissociable group has an alicyclic skeleton. The term“constitutional unit having an alicyclic skeleton” is used to mean aconstitutional unit, which has a structure having one or more cyclichydrocarbon groups.

The present invention relates to the above-described resist polymer,wherein the above-described constitutional unit having anacid-dissociable group is at least one selected from the groupconsisting of the following formulas (3-1-1), (3-2-1), and (3-3-1):

(wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups,

wherein, in formula (3-2-1), R³² represents a hydrogen atom or a methylgroup; each of R² and R³ independently represents an alkyl group having1 to 3 carbon atoms; X² represents a linear or branched alkyl grouphaving 1 to 6 carbon atoms that may have, as a substituent, at least oneselected from the group consisting of a hydroxy group, a carboxy group,an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6carbon atoms, a carboxy group that is esterified with alcohol having 1to 6 carbon atoms, and an amino group, a hydroxy group, a carboxy group,an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6carbon atoms, a carboxy group that is esterified with alcohol having 1to 6 carbon atoms, or an amino group; and n2 represents an integerbetween 0 and 4, and when n2 is 2 or greater, X² may be a plurality ofdifferent groups, and

wherein, in formula (3-3-1), R³³ represents a hydrogen atom or a methylgroup; R⁴ represents an alkyl group having 1 to 3 carbon atoms; X³represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups.)

It is to be noted that, in formulas (3-1-1), (3-2-1), and (3-3-1),positions substituted with X¹, X², and X³ may be any positions in thecyclic structures.

In this polymer, constitutional units represented by formulas (3-1-1),(3-2-1), and (3-3-1) are not necessarily all the same, but may be amixture of two or more kinds thereof.

The present invention relates to the above-described resist polymer,wherein the above-described constitutional unit having anacid-dissociable group is a constitutional unit represented by thefollowing formula (3-5):

(wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup.)

It is to be noted that, in this polymer, constitutional unitsrepresented by formula (3-5) are not necessarily all the same, but maybe a mixture of two or more kinds thereof.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit represented by theabove-described formula (1), at least one constitutional unit selectedfrom the group consisting of those represented by the above-describedformulas (3-1-1), (3-2-1), (3-3-1), and (3-5), and at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (4-1), (4-2), (4-3), (4-5),(4-6), and (4-10).

It is to be noted that, in this polymer, constitutional unitsrepresented by formula (1), at least one constitutional unit selectedfrom the group consisting of those represented by the above-describedformulas (3-1-1), (3-2-1), (3-3-1), and (3-5), and at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (4-1), (4-2), (4-3), (4-5),(4-6), and (4-10), are not necessarily all the same, but may be amixture of two or more kinds thereof. In addition, in this polymer, eachconstitutional unit may have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit represented by theabove-described formula (1), at least one constitutional unit selectedfrom the group consisting of those represented by the above-describedformulas (3-1-1), (3-2-1), (3-3-1), and (3-5), and at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (4-1), (4-2), (4-3), and(4-10).

It is to be noted that, in this polymer, constitutional unitsrepresented by formula (1), at least one constitutional unit selectedfrom the group consisting of those represented by the above-describedformulas (3-1-1), (3-2-1), (3-3-1), and (3-5), and at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (4-1), (4-2), (4-3), and(4-10), are not necessarily all the same, but may be a mixture of two ormore kinds thereof. In addition, in this polymer, each constitutionalunit may have any given sequence. Accordingly, this polymer may be arandom copolymer, an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (3-1-1),(3-3-1), and (3-5), and at least one constitutional unit represented bythe following formula (4-7):

(wherein, in formula (4-7), R⁴⁷ represents a hydrogen atom or a methylgroup.)

It is to be noted that, in this polymer, at least one constitutionalunit selected from the group consisting of those represented by theabove-described formulas (2) and (1-1), at least one constitutional unitselected from the group consisting of those represented by theabove-described formulas (3-1-1), (3-3-1), and (3-5), and constitutionalunits represented by the above-described formula (4-7), are notnecessarily all the same, but may be a mixture of two or more kindsthereof. In addition, in this polymer, each constitutional unit may haveany given sequence. Accordingly, this polymer may be a random copolymer,an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein the total ratio of at least one constitutional unit selectedfrom those represented by the above-described formulas (2) and (1-1) isbetween 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (3-1-1), (3-3-1), and (3-5)is between 30% and 60% by mole, and the total ratio of theconstitutional unit represented by the above-described formula (4-7) isbetween 30% and 60% by mole.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (3-1-1),(3-3-1), and (3-5), and at least one constitutional unit represented bythe following formula (4-8):

(wherein, in formula (4-8), R⁴⁸ represents a hydrogen atom or a methylgroup.)

It is to be noted that, in this polymer, at least one constitutionalunit selected from the group consisting of those represented by theabove-described formulas (2) and (1-1), at least one constitutional unitselected from the group consisting of those represented by theabove-described formulas (3-1-1), (3-3-1), and (3-5), and constitutionalunits represented by the above-described formula (4-8), are notnecessarily all the same, but may be a mixture of two or more kindsthereof. In addition, in this polymer, each constitutional unit may haveany given sequence. Accordingly, this polymer may be a random copolymer,an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein the total ratio of at least one constitutional unit selectedfrom those represented by the above-described formulas (2) and (1-1) isbetween 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (3-1-1), (3-3-1), and (3-5)is between 30% and 60% by mole, and the total ratio of theconstitutional unit represented by the above-described formula (4-8) isbetween 30% and 60% by mole.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (3-1-1),(3-3-1), and (3-5), and at least one constitutional unit represented bythe following formula (4-11):

(wherein, in formula (4-11), R⁴¹¹ represents a hydrogen atom or a methylgroup.)

It is to be noted that, in this polymer, at least one constitutionalunit selected from the group consisting of those represented by theabove-described formulas (2) and (1-1), at least one constitutional unitselected from the group consisting of those represented by theabove-described formulas (3-1-1), (3-3-1), and (3-5), and constitutionalunits represented by the above-described formula (4-11), are notnecessarily all the same, but may be a mixture of two or more kindsthereof. In addition, in this polymer, each constitutional unit may haveany given sequence. Accordingly, this polymer may be a random copolymer,an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein the total ratio of at least one constitutional unit selectedfrom those represented by the above-described formulas (2) and (1-1) isbetween 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (3-1-1), (3-3-1), and (3-5)is between 30% and 60% by mole, and the total ratio of theconstitutional unit represented by the above-described formula (4-11) isbetween 30% and 60% by mole.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (3-1-1),(3-3-1), and (3-5), and at least one constitutional unit represented bythe following formula (4-9):

(wherein, in formula (4-9), R⁴⁹ represents a hydrogen atom or a methylgroup.)

It is to be noted that, in this polymer, at least one constitutionalunit selected from the group consisting of those represented by theabove-described formulas (2) and (1-1), at least one constitutional unitselected from the group consisting of those represented by theabove-described formulas (3-1-1), (3-3-1), and (3-5), and constitutionalunits represented by the above-described formula (4-9), are notnecessarily all the same, but may be a mixture of two or more kindsthereof. In addition, in this polymer, each constitutional unit may haveany given sequence. Accordingly, this polymer may be a random copolymer,an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein the total ratio of at least one constitutional unit selectedfrom those represented by the above-described formulas (2) and (1-1) isbetween 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (3-1-1), (3-3-1), and (3-5)is between 30% and 60% by mole, and the total ratio of theconstitutional unit represented by the above-described formula (4-9) isbetween 30% and 60% by mole.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (3-1-1),(3-3-1), and (3-5), and at least one constitutional unit selected fromthe group consisting of those represented by the above-describedformulas (4-2) and (4-3).

It is to be noted that, in this polymer, at least one constitutionalunit selected from the group consisting of those represented by theabove-described formulas (2) and (1-1), at least one constitutional unitselected from the group consisting of those represented by theabove-described formulas (3-1-1), (3-3-1), and (3-5), and at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (4-2) and (4-3), are notnecessarily all the same, but may be a mixture of two or more kindsthereof. In addition, in this polymer, each constitutional unit may haveany given sequence. Accordingly, this polymer may be a random copolymer,an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein the total ratio of at least one constitutional unit selectedfrom those represented by the above-described formulas (2) and (1-1) isbetween 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (3-1-1), (3-3-1), and (3-5)is between 30% and 60% by mole, and the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (4-2) and (4-3) is between30% and 60% by mole.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit represented by theabove-described formulas (1), at least one constitutional unit selectedfrom the group consisting of those represented by the above-describedformulas (3-1-1), (3-2-1), and (3-3-1), and at least one constitutionalunit selected from the group consisting of those represented by theabove-described formulas (4-7) and (4-8).

It is to be noted that, in this polymer, constitutional unitsrepresented by the above-described formula (1), at least oneconstitutional unit selected from the group consisting of thoserepresented by the above-described formulas (3-1-1), (3-2-1) and(3-3-1), and at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (4-7)and (4-8), are not necessarily all the same, but may be a mixture of twoor more kinds thereof. In addition, in this polymer, each constitutionalunit may have any given sequence. Accordingly, this polymer may be arandom copolymer, an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein the total ratio of the constitutional unit represented by theabove-described formula (1) is between 5% and 30% by mole, the totalratio of at least one constitutional unit selected from the groupconsisting of those represented by the above-described formulas (3-1-1),(3-2-1), and (3-3-1) is between 30% and 60% by mole, and the total ratioof at least one constitutional unit selected from the group consistingof those represented by the above-described formulas (4-7) and (4-8) isbetween 30% and 60% by mole.

The present invention relates to the above-described resist polymer,which comprises at least one constitutional unit represented by theabove-described formula (2), at least one constitutional unitrepresented by the above-described formula (3-1-1), and at least oneconstitutional unit represented by the above-described formula (4-8).

It is to be noted that, in this polymer, constitutional unitsrepresented by the above-described formula (2), constitutional unitsrepresented by the above-described formula (3-1-1), and constitutionalunits represented by the above-described formula (4-8), are notnecessarily all the same, but may be a mixture of two or more kindsthereof. In addition, in this polymer, each constitutional unit may haveany given sequence. Accordingly, this polymer may be a random copolymer,an alternating copolymer, or a block copolymer.

The present invention relates to the above-described resist polymer,wherein the total ratio of the constitutional unit represented by theabove-described formula (2) is between 5% and 30% by mole, the totalratio of the constitutional unit represented by the above-describedformula (3-1-1) is between 30% and 60% by mole, and the total ratio ofthe constitutional unit represented by the above-described formula (4-8)is between 30% and 60% by mole.

The present invention relates to the above-described resist polymer,which further comprises at least one constitutional unit selected fromthe group consisting of those represented by the following formulas(3-1-2) and (3-4):

(wherein, in formula (3-1-2), R³¹ represents a hydrogen atom or a methylgroup; R¹¹ represents a hydrogen atom; X¹ represents a linear orbranched alkyl group having 1 to 6 carbon atoms that may have, as asubstituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, a cyano group,and an amino group, a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, or an amino group; and n1 represents an integer between 0 and 4,and when n1 is 2 or greater, X¹ may be a plurality of different groups,and

wherein, in formula (3-4), R³⁴ represents a hydrogen atom or a methylgroup; X⁴ represents a linear or branched alkyl group having 1 to 6carbon atoms that may have, as a substituent, at least one selected fromthe group consisting of a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, and an amino group, a hydroxy group, a carboxy group, an acylgroup having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbonatoms, a carboxy group that is esterified with alcohol having 1 to 6carbon atoms, or an amino group; and n4 represents an integer between 0and 4, and when n4 is 2 or greater, X⁴ may be a plurality of differentgroups.)

It is to be noted that, in formulas (3-1-2) and (3-4), positionssubstituted with X¹ and X⁴ may be any positions in the cyclicstructures.

In this polymer, constitutional units represented by formulas (3-1-2)and (3-4) are not necessarily all the same, but may be a mixture of twoor more kinds thereof.

The present invention relates to the above-described resist polymer,which has a mass average molecular weight between 1,000 and 100,000.

The present invention relates to the above-described resist polymer,which has a mass average molecular weight between 5,000 and 8,000.

The present invention relates to the above-described resist polymer,which further comprises a constitutional unit derived from a chaintransfer agent.

It is to be noted that, in this polymer, constitutional units derivedfrom a chain transfer agent are not necessarily all the same, but may bea mixture of two or more kinds thereof.

The present invention relates to the above-described resist polymer,which is produced by carrying out polymerization, while adding dropwiseto a polymerization reactor a solution containing monomers that becomeconstitutional units of a polymer of interest as a result of thepolymerization.

In addition, the present invention relates to a resist composition,which comprises the above-described resist polymer.

Moreover, the present invention relates to a chemically amplified resistcomposition, which comprises the above-described resist polymer and aphotoacid generator.

The present invention relates to the above-described chemicallyamplified resist composition, which further comprises anitrogen-containing compound.

Furthermore, the present invention relates to a method of producing apattern, which comprises the steps of applying the above-describedresist composition onto a substrate to be processed, exposing thesubstrate to a light with a wavelength of 250 nm or shorter, anddeveloping it with a developing solution.

The present invention relates to the above-described method of producinga pattern, wherein the light used for exposure is an ArF excimer laser.

Still further, the present invention relates to a method of producing apattern, which comprises the steps of applying the above-describedresist composition onto a substrate to be processed, exposing thesubstrate to an electron beam, and developing it with a developingsolution.

The resist polymer of the present invention comprises a constitutionalunit represented by the above formula (1), a constitutional unit havingan acid-dissociable group, and a constitutional unit having a lactoneskeleton represented by at least one selected from the group consistingof the above formulas (4-1), (4-2), (4-3), (4-5), (4-6), and (4-10). Theterm “acid-dissociable group” is used herein to mean a group that isdecomposed or dissociated by the action of acid.

Among others, the constitutional unit represented by the above formula(1) is preferably one having a norbornane ring, and a constitutionalunit represented by the above formula (2) is more preferable.

Among others, preferred examples of a constitutional unit having alactone skeleton may include a constitutional unit represented by theabove (4-1), a constitutional unit represented by the above (4-2), aconstitutional unit represented by the above (4-3), and a constitutionalunit represented by the above (4-10).

As stated above, constitutional units represented by the above formula(1) are not necessarily all the same, but may be a mixture of two ormore kinds thereof. Likewise, constitutional units having anacid-dissociable group and constitutional units having a lactoneskeleton are not necessarily all the same, but may be a mixture of twoor more kinds thereof. In addition, in this polymer, each constitutionalunit may have any given sequence. Accordingly, this polymer may be arandom copolymer, an alternating copolymer, or a block copolymer.

The resist polymer of the present invention comprises a constitutionalunit having a cyano group having cyclic hydrocarbon group represented bythe above formula (1), a constitutional unit having an acid-dissociablegroup, and a constitutional unit having a lactone skeleton representedby at least one selected from the group consisting of the above formulas(4-1), (4-2), (4-3), (4-5), (4-6), and (4-10). With such a structure,the resist polymer of the present invention exhibits the same degree ofhigh sensitivity and resolution as those of the conventional polymersused for resists, and provides a better resist pattern and improvedadhesiveness to a substrate, inhibiting occurrence of line edgeroughness or generation of microgels.

Moreover, using the resist polymer of the present invention, a uniformresist pattern size can be achieved on the surface of a substrate, evenwhen a large substrate with a diameter of 300 mm or greater is used.Furthermore, a resist pattern to be formed is not significantlyinfluenced by the PEB temperature. That is to say, the present inventioncan be reduced the dependency of the PEB temperature.

In order to obtain the aforementioned effects of the present invention,all of the constitutional unit represented by the above formula (1), theconstitutional unit having an acid-dissociable group, and at least oneconstitutional unit having a lactone skeleton represented by at leastone selected from the group consisting of the above formulas (4-1),(4-2), (4-3), (4-5), (4-6), and (4-10), are essential. If the polymer ofthe present invention lacked any one of these constitutional units,excellent effects could not be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

1. Monomer Containing Cyano Group used for the Resist Polymer of thePresent Invention

The constitutional unit represented by the above formula (1) in theresist polymer of the present invention is derived from a (meth)acrylicacid ester derivative having a cyano group represented by formula (5)indicated below. In other words, the resist polymer of the presentinvention is obtained by copolymerization of a monomer compositioncontaining a (meth)acrylic acid ester derivative having a cyano grouprepresented by formula (5) indicated below. Such a (meth)acrylic acidester derivative represented by the following formula (5) may be usedalone or in combination.

(wherein, in formula (5), R⁰¹ represents a hydrogen atom or a methylgroup; R⁰² represents a hydrogen atom or an alkyl group having 1 to 4carbon atoms; Z represents an atomic group that constitutes a cyclichydrocarbon group together with a carbon atom constituting an ester bondand a carbon atom to which a cyano group binds; and p represents aninteger between 1 and 4,

provided that when p is 2 or greater, cyano groups may bind to a singlecarbon atom or different carbon atoms.)

The term “(meth)acrylic acid” is a generic name for both acrylic acidand methacrylic acid.

In formula (5), R⁰² represents a hydrogen atom or an alkyl group having1 to 4 carbon atoms. Such an alkyl group may be either linear orbranched. Examples of such an alkyl group may include a methyl group, anethyl group, a propyl group, and an isopropyl group. In terms ofsolubility in organic solvents, R⁰² is preferably a hydrogen atom or amethyl group, and more preferably a hydrogen atom. In addition, in termsof stability of the polymer and easy handlability, a hydrogen atom isparticularly preferable.

In formula (5), Z represents an atomic group that constitutes a cyclichydrocarbon group, and preferably a bridged cyclic hydrocarbon group,together with a carbon atom constituting an ester bond and a carbon atomto which a cyano group binds. The number of carbon atoms contained insuch a cyclic hydrocarbon group is not particularly limited. It ispreferably between 7 and 20. This cyclic hydrocarbon group may have asubstituent as well as a cyano group. Examples of such a substituent mayinclude: a linear or branched alkyl group having 1 to 6 carbon atomsthat may have at least one radical selected from the group consisting ofa hydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup; a hydroxy group; a carboxy group; an acyl group having 1 to 6carbon atoms; an alkoxy group having 1 to 6 carbon atoms; a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms; and anamino group.

In terms of high dry etching resistance required for resists, Z informula (5) is preferably an atomic group that constitutes a bridgedcyclic hydrocarbon group together with a carbon atom constituting anester bond and a carbon atom to which a cyano group binds.

Examples of Z in formula (5) may include atomic groups having a cyclicterpene hydrocarbon such as a norbornane ring, an adamantane ring, atetracyclododecane ring, a dicyclopentane ring, tricyclodecane ring, adecahydronaphthalene ring, a polyhydroanthracene ring, a camphor ring, acholesteric ring, or the like. In terms of high dry-etching resistancerequired for resists, Z is preferably an atomic group having a cyclicterpene hydrocarbon such as a norbornane ring, an adamantane ring, atetracyclododecane ring, a dicyclopentane ring, or a tricyclodecanering. An atomic group having a norbornane ring represented by formula(11-1) indicated below, a tetracyclododecane ring represented by formula(11-2) indicated below, and an adamantane ring represented by formula(11-3) indicated below, are more preferable. Of these, an atomic grouphaving a norbornane ring is particularly preferable because it isexcellent in terms of copolymerizability with other monomers.

In formula (5), p represents the number of cyano groups contained in thecyclic hydrocarbon group. p represents an integer between 1 and 4. Interms of sensitivity and resolution, p is preferably 1 or 2, and morepreferably 1.

When p is 2 or greater, cyano groups may bind to a single carbon atom ormay bind to different carbon atoms. In terms of adhesiveness to metalsurface or the like, it is preferable that cyano groups bind todifferent carbon atoms.

The positions of substitution of cyano groups are not particularlylimited. When Z is a norbornyl ring for example, if it is substituted atposition 5 with a (meth)acryloyl group, the positions of substitution ofcyano groups are preferably position 2 and/or position 3.

Specific examples of a monomer represented by the above formula (5) mayinclude monomers represented by formulas (6-1) to (6-16) indicatedbelow. In formulas (6-1) to (6-16), R represents a hydrogen atom or amethyl group.

In terms of dry etching resistance, preferred examples of a monomerrepresented by the above formula (5) may include a monomer representedby the above formula (6-1), a monomer represented by the above formula(6-3), a monomer represented by the above formula (6-4), and a monomerrepresented by the above formula (6-6). Of these, a monomer representedby the above formula (6-1), a monomer represented by the above formula(6-4), and a monomer represented by the above formula (6-6), are morepreferable. A monomer represented by the above formula (6-1) isparticularly preferable in terms of copolymerizability with othermonomers.

The constitutional unit represented by the above formula (1-1) is anexample of the constitutional unit represented by the above formula (1)in the resist polymer of the present invention. The constitutional unitrepresented by the above formula (1-1) is derived from a (meth)acrylicacid ester derivative having a cyano group represented by formula (5-1)indicated below. In other words, the resist polymer of the presentinvention containing the constitutional unit represented by the aboveformula (1-1) is obtained by copolymerization of a monomer compositioncontaining a (meth)acrylic acid ester derivative having a cyano grouprepresented by formula (5-1) indicated below. Such a (meth)acrylic acidester derivative represented by the following formula (5-1) may be usedalone or in combination.

(wherein, in formula (5-1), R⁰¹ represents a hydrogen atom or a methylgroup; R⁰³ represents a hydrogen atom, or a linear or branched alkylgroup having 1 to 6 carbon atoms; and each of A⁰¹ and A⁰² independentlyrepresents a hydrogen atom, or a linear or branched alkyl group having 1to 4 carbon atoms, or A⁰¹ and A⁰² together represent —O—, —S—, —NH—, oran alkylene chain having 1 to 6 carbon atoms.)

In formula (5-1), R⁰³ represents a hydrogen atom, or a linear orbranched alkyl group having 1 to 6 carbon atoms. In terms of excellentcopolymerizability with other monomers, an ethyl group, a methyl group,and a hydrogen atom are preferable as R⁰³, and of these, a methyl groupis more preferable.

In formula (5-1), each of A⁰¹ and A⁰² independently represents ahydrogen atom, or a linear or branched alkyl group having 1 to 4 carbonatoms, or A⁰¹ and A⁰² together represent —O—, —S—, —NH—, or an alkylenechain having 1 to 6 carbon atoms. In terms of excellent solubility insolvents, both A⁰¹ and A⁰² are preferably hydrogen atoms. In terms ofexcellent dry etching resistance, A⁰¹ and A⁰² preferably together form—CH₂— or —CH₂—CH₂—.

Specific examples of the monomer represented by the above formula (5-1)may include those represented by formulas (6-17) and (6-18) indicatedbelow. R in formulas (6-17) and (6-18) represents a hydrogen atom or amethyl group.

In addition, another example of the constitutional unit represented bythe above formula (1) contained in the resist polymer of the presentinvention may be a constitutional unit, wherein, in the above formula(1), p is 1, and a cyano group binds to a carbon atom that is adjacentto the ester carbon atom. The bond between the ester carbon atom and acarbon atom to which a cyano group binds is generally a single bond.

In such a case, an atomic group having a cyclohexane ring is preferableas Z in formula (1) because it is excellent in terms ofcopolymerizability with other monomers. In addition, in terms of highdry etching resistance required for resists, an atomic group having abridged cyclic hydrocarbon group is preferable as Z. Particularlypreferred examples of Z may include an atomic group having a cyclohexanering, an atomic group having an adamantane ring, an atomic group havinga camphor ring, an atomic group having a norbornane ring, and an atomicgroup having a pinane ring.

As such a constitutional unit represented by the above formula (1),which has a cyano group binding to a carbon atom that is adjacent to theester carbon atom, the constitutional unit represented by the aboveformula (1-2) is preferable. The constitutional unit represented by theabove formula (1-2) is derived from a (meth)acrylic acid esterderivative having a cyano group represented by formula (5-2) indicatedbelow. In other words, the resist polymer containing the constitutionalunit represented by the above formula (1-2) is obtained bycopolymerization of a monomer composition containing a (meth)acrylicacid ester derivative having a cyano group represented by formula (5-2)indicated below. Such a (meth)acrylic acid ester derivative representedby the following formula (5-2) may be used alone or in combination:

(wherein, in formula (5-2), R⁰¹ represents a hydrogen atom or a methylgroup; and each of R⁰⁴, R⁰⁵, R⁰⁶, and R⁰⁷ independently represents ahydrogen atom, or a linear or branched alkyl group having 1 to 4 carbonatoms, or two out of R⁰⁴, R⁰⁵, R⁰⁶, and R⁰⁷ together represent analkylene chain having 1 to 6 carbon atoms.)

In formula (5-2), each of R⁰⁴, R⁰⁵, R⁰⁶, and R⁰⁷ independentlyrepresents a hydrogen atom, or a linear or branched alkyl group having 1to 4 carbon atoms, or two out of R⁰⁴, R⁰⁵, R⁰⁶, and R⁰⁷ togetherrepresent an alkylene chain having 1 to 6 carbon atoms. In terms ofexcellent copolymerizability with other monomers, all of R⁰⁴, R⁰⁵, R⁰⁶,and R⁰⁷ are preferably hydrogen atoms. In terms of excellent dry etchingresistance, with regard to R⁰⁴, R⁰⁵, R⁰⁶, and R⁰⁷, it is preferable thatR⁰⁴ and R⁰⁷ together form —CH₂— or —CH₂—CH₂—.

Specific examples of the monomer represented by the above formula (5-2)may include monomers represented by formulas (6-19) and (6-20) indicatedbelow. R in formulas (6-19) and (6-20) represents a hydrogen atom or amethyl group.

The (meth)acrylic acid ester derivative containing a cyano grouprepresented by the above formula (5) can be produced by processes (I) or(II) shown below, for example. Process (I) shown below indicates aprocess of producing the monomer represented by the above formula (6-1),and process (II) shown below indicates a process of producing themonomer represented by the above formula (6-17). Other monomersrepresented by the above formula (5) can also be produced in the samemanner.

Raw materials, such as (meth)acrylonitrile, cyclopentadiene,2-methoxybutadiene, (meth)acrylic acid, and a derivative thereof, can beproduced by known methods. Otherwise, commercially available productscan also be used.

A cycloaddition reaction between (meth)acrylonitrile and cyclopentadieneor 2-methoxybutadiene can easily be carried out by known methods. Such areaction is preferably carried out, using a catalyst such as Lewis acidas necessary, in no solvents or in a solvent such as methanol.

An addition reaction of adding acrylic acid or methacrylic acid to anunsaturated bond is preferably carried out, using an acid catalyst, inno solvents or in a solvent such as toluene, with excessive acrylic acidor methacrylic acid. The type of an acid catalyst used in this additionreaction is not particularly limited. Examples of such an acid catalystmay include hydrochloric acid, sulfuric acid, nitric acid,p-toluenesulfonic acid, acetic acid, trifluoroacetic acid, andtrifluoromethanesulfonic acid. Among these acid catalysts, sulfuricacid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid arepreferable in terms of reaction rate. Trifluoromethanesulfonic acid ismore preferable.

The product obtained from the above reaction may include severalstructural isomers, geometric isomers, and optical isomers, in somecases. In the present invention, a mixture consisting of two or moretypes of isomers may be used, or a specific isomer may be used singlyafter purification. In the present invention, a mixture consisting ofisomers may directly be used in a polymerization reaction. Moreover,even if the product contains a reaction intermediate, it can directly beused in a polymerization reaction. The above reaction product may bepurified by simple distillation, thin film distillation,recrystallization, column chromatography, or the like, as necessary.

The (meth)acrylic acid ester derivative containing a cyano grouprepresented by the above formula (5-2) can be produced by process (III)shown below, for example. Process (III) shown below indicates a processof producing the monomer represented by the above formula (6-19). Othermonomers represented by the above formula (5-2) can also be produced inthe same manner. R in formula (III) represents a hydrogen atom or amethyl group.

Raw material, epoxide such as cyclohexene oxide, can be produced byknown methods. Otherwise, commercially available products can also beused.

In the present production method, epoxide is first allowed to react witha cyanating agent, so as to synthesize β-cyanohydrin. Examples of acyanating agent used in this cyanation reaction may include hydrogencyanide, sodium cyanide, potassium cyanide, trimethylsilylcyan, andacetonecyanhydrin. Of these, in terms of safety, sodium cyanide,potassium cyanide, and trimethylsilylcyan are preferable. In terms ofinexpensiveness, hydrogen cyanide, sodium cyanide, and potassium cyanideare preferable. This cyanation reaction progresses either under acidicconditions or under alkaline conditions. In the present productionmethod, in terms of reaction rate, it is preferable that the cyanationreaction be carried out using potassium cyanide as a cyanating agentunder alkaline conditions.

The obtained β-cyanohydrin may be purified by known methods such asdistillation or column chromatography, or it may directly be used in thesubsequent reaction without being purified.

Subsequently, β-cyanohydrin is converted into (meth)acrylic acid ester.The reaction of converting β-cyanohydrin into (meth)acrylic acid estercan be carried out by known methods such as esterification ortransesterification. Examples of an esterifying agent used in thisreaction may include (meth)acrylic acid, (meth)acrylic acid chloride,(meth)acrylic acid anhydride, and (meth)acrylic acid ester. Of these, interms of reaction rate, (meth)acrylic acid chloride and (meth)acrylicacid anhydride are preferable as an esterifying agent. Moreover, in sucha reaction of converting β-cyanohydrin into (meth)acrylic acid ester, acatalyst such as Lewis acid may be used, as necessary.

The product obtained from the above reaction may include severalstructural isomers, geometric isomers, and optical isomers, in somecases. In the present invention, a mixture consisting of two or moretypes of isomers may be used, or a specific isomer may be used singlyafter purification. In the present invention, a mixture consisting ofisomers may directly be used in a polymerization reaction. Moreover,even if the product contains a reaction intermediate, it can directly beused in a polymerization reaction. The above reaction product may bepurified by known methods such as distillation or column chromatography,as necessary.

The cyano group having (meth)acrylic acid ester derivative representedby the above formula (6-18) can be produced by the following process(IV), for example:

Cyano norbornene used as a raw material can be produced by the samemethod as the above process (I).

In the present production method, first, an epoxidization reaction ofcyano norbornene is carried out. In such an epoxidization reaction ofcyano norbornene, cyano norbornene is generally allowed to react with anoxidizing agent. Examples of an oxidizing agent used herein may includehydrogen peroxide, peracetic acid, perbenzoic acid, andm-chloroperbenzoic acid. Of these, hydrogen peroxide is preferable as anoxidizing agent in terms of easy handlability. In terms of excellentreactivity, m-chloroperbenzoic acid is preferable.

Subsequently, a ring-opening reaction of epoxide is carried out. Such aring-opening reaction of epoxide is generally carried out under acidicconditions or basic conditions. In addition, a catalyst such as Lewisacid may be used, as necessary. In the present production method, amethod of adding methanol or metal methoxide to epoxide (allowing themto react with epoxide) under basic conditions is preferably appliedbecause it is excellent in terms of reactivity.

The obtained compound may be purified by known methods such asdistillation or column chromatography, or it may directly be used in thesubsequent reaction without being purified.

The subsequent reaction of converting the compound into (meth)acrylicacid ester can be carried out by the above-described method, that is,the reaction of converting β-cyanohydrin into (meth)acrylic acid ester.

The product obtained from the above reaction may include severalstructural isomers, geometric isomers, and optical isomers, in somecases. In the present invention, a mixture consisting of two or moretypes of isomers may be used, or a specific isomer may be used singlyafter purification. In the present invention, a mixture consisting ofisomers may directly be used in a polymerization reaction. Moreover,even if the product contains a reaction intermediate, it can directly beused in a polymerization reaction. The above reaction product may bepurified by known methods such as distillation or column chromatography,as necessary.

2. The Resist Polymer of the Present Invention

The resist polymer of the present invention is obtained bycopolymerization of a monomer composition, which comprises at least one(meth)acrylic acid ester derivative containing a cyano group representedby the above formula (5), at least one monomer having anacid-dissociable group, and at least one monomer having a lactoneskeleton. It comprises a constitutional unit represented by the aboveformula (1), a constitutional unit having an acid-dissociable group, anda constitutional unit having a lactone skeleton.

In addition, the resist polymer of the present invention is preferablyobtained by copolymerization of a monomer composition, which comprisesat least one (meth)acrylic acid ester derivative containing a cyanogroup represented by the above formula (6-1) and/or (6-17), at least onemonomer having an acid-dissociable group, and at least one monomerhaving a lactone skeleton. The resist polymer of the present inventionis particularly preferably obtained by copolymerization of a monomercomposition, which comprises at least one (meth)acrylic acid esterderivative containing a cyano group represented by the above formula(6-1), at least one monomer having an acid-dissociable group, and atleast one monomer having a lactone skeleton. It comprises aconstitutional unit represented by the above formula (2), aconstitutional unit having an acid-dissociable group, and aconstitutional unit having a lactone skeleton.

The resist polymer of the present invention may comprise at least oneconstitutional unit represented by the above formula (1) other than theconstitutional unit represented by the above formula (2), and at leastone constitutional unit represented by the above formula (2).

In addition, each constitutional unit in the resist polymer of thepresent invention may have any given sequence. Accordingly, this polymermay be a random copolymer, an alternating copolymer, or a blockcopolymer.

The total ratio of the constitutional unit represented by the aboveformula (1) (which includes the constitutional unit represented by theabove formula (2) and the constitutional unit represented by the aboveformula (1-1)) in the resist polymer of the present invention ispreferably 5% or more by mole, and more preferably 10% or more by mole,in terms of good resist pattern. Moreover, the total ratio of theconstitutional unit represented by the above formula (1) (which includesthe constitutional unit represented by the above formula (2) and theconstitutional unit represented by the above formula (1-1)) in theresist polymer of the present invention is preferably 30% or less bymole, and more preferably 25% or less by mole, in terms of sensitivityand resolution.

The total ratio of the constitutional unit having an acid-dissociablegroup in the resist polymer of the present invention is preferably 30%or more by mole, and more preferably 35% or more by mole, in terms ofsensitivity and resolution. Moreover, the total ratio the constitutionalunit having an acid-dissociable group in the resist polymer of thepresent invention is preferably 60% or less by mole, and more preferably50% or less by mole, in terms of adhesiveness to the metal surface orthe like.

The total ratio of the constitutional unit having a lactone skeleton inthe resist polymer of the present invention is preferably 30% or more bymole, and more preferably 35% or more by mole, in terms of adhesivenessto the metal surface or the like. Moreover, the total ratio theconstitutional unit having a lactone skeleton in the resist polymer ofthe present invention is preferably 60% or less by mole, and morepreferably 50% or less by mole, in terms of sensitivity and resolution.

The constitutional unit having an acid-dissociable group will bedescribed.

The type of an acid-dissociable group is not particularly limited, aslong as it is a group that is decomposed or dissociated by the action ofacid. Examples of such an acid-dissociable group may include thoserepresented by the following formulas (12-1) to (12-9):

(wherein, in formula (12-1), R¹⁰¹ represents a tertiary alkyl grouphaving 4 to 20 carbon atoms, and s represents an integer between 0 and10;

wherein, in formula (12-2), each of R¹⁰² and R¹⁰³ independentlyrepresents a hydrogen atom, or a linear, branched, or cyclic alkyl grouphaving 1 to 18 carbon atoms, and R¹⁰⁴ represents a monovalenthydrocarbon group having 1 to 20 carbon atoms that may contain aheteroatom, or R¹⁰² and R¹⁰³, R¹⁰² and R¹⁰⁴, or R¹⁰³ and R¹⁰⁴, representa cyclic hydrocarbon group together with carbon atoms to which theybind;

wherein, in formula (12-3), each of R¹⁰⁵, R¹⁰⁶, and R¹⁰⁷ independentlyrepresents a linear, branched, or cyclic alkyl group having 1 to 18carbon atoms, or R¹⁰⁵ and R¹⁰⁶, R¹⁰⁵ and R¹⁰⁷, or R¹⁰⁶ and R¹⁰⁷,represent a cyclic hydrocarbon group together with carbon atoms to whichthey bind;

wherein, in formula (12-4), each of R¹⁰⁸, R¹⁰⁹, and R¹¹⁰ independentlyrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group, or an aryl group, or R¹⁰⁸ and R¹⁰⁹, R¹⁰⁸ and R¹¹⁰, orR¹⁰⁹ and R¹¹⁰, represent a cyclic hydrocarbon group together with carbonatoms to which they bind, provided that at least two out of R¹⁰⁸, R¹⁰⁹,and R¹¹⁰ represent groups other than hydrogen atoms, and A¹⁰¹ representsa divalent aromatic hydrocarbon group that may have a monocyclic orpolycyclic substituent;

wherein, in formula (12-5), each of R¹¹¹ and R¹¹² independentlyrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group, or an aryl group, and R¹¹³ represents an alkyl group oran aryl group, or R¹¹¹ and R¹¹², R¹¹¹ and R¹¹³, or R¹¹² and R¹¹³,represent a cyclic hydrocarbon group or an aliphatic heterocyclic ringtogether with carbon atoms or oxygen atoms to which they bind, providedthat at least two out of R¹¹¹, R¹¹², and R¹¹³ represent groups otherthan hydrogen atoms, and A¹⁰² represents a divalent aromatic hydrocarbongroup that may have a monocyclic or polycyclic substituent;

wherein, in formula (12-6), each of R¹¹⁴, R¹¹⁵, and R¹¹⁶ independentlyrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group, or an aryl group, or R¹¹⁴ and R¹¹⁵, R¹¹⁴ and R¹¹⁶, orR¹¹⁵ and R¹¹⁶, represent an aliphatic heterocyclic ring together withsilicon atoms to which they bind, provided that at least two out ofR¹¹⁴, R¹¹⁵, and R¹¹⁶ represent groups other than hydrogen atoms, andA¹⁰³ represents a divalent aromatic hydrocarbon group that may have amonocyclic or polycyclic substituent;

wherein, in formula (12-7), each of R¹¹⁷, R¹¹⁸, and R¹¹⁹ independentlyrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group, or an aryl group, or R¹¹⁷ and R¹¹⁸, R¹¹⁷ and R¹¹⁹, orR¹¹⁸ and R¹¹⁹, represent a cyclic hydrocarbon group together with carbonatoms to which they bind, provided that at least two out of R¹¹⁷, R¹¹⁸,and R¹¹⁹ represent groups other than hydrogen atoms, and A¹⁰⁴ representsa divalent aromatic hydrocarbon group that may have a monocyclic orpolycyclic substituent;

wherein, in formula (12-8), each of R¹²⁰ and R¹²¹ independentlyrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group, or an aryl group, and R¹²² represents an alkyl group oran aryl group, or R¹²⁰ and R¹²¹, R¹²⁰ and R¹²², or R¹²¹ and R¹²²,represent a cyclic hydrocarbon group or an aliphatic heterocyclic ringtogether with carbon atoms or oxygen atoms to which they bind, providedthat at least two out of R¹²⁰, R¹²¹, and R¹²² represent groups otherthan hydrogen atoms, and A¹⁰⁵ represents a divalent aromatic hydrocarbongroup that may have a monocyclic or polycyclic substituent; and

wherein, in formula (12-9), each of R¹²³, R¹²⁴, and R¹²⁵ independentlyrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group, or an aryl group, or R¹²³ and R¹²⁴, R¹²³ and R¹²⁵, orR¹²⁴ and R¹²⁵, represent an aliphatic heterocyclic ring together withsilicon atoms to which they bind, provided that at least two out ofR¹²³, R¹²⁴, and R¹²⁵ represent groups other than hydrogen atoms, andA¹⁰⁶ represents a divalent aromatic hydrocarbon group that may have amonocyclic or polycyclic substituent.)

In formula (12-1), R¹⁰¹ represents a tertiary alkyl group having 4 to 20carbon atoms, and preferably 4 to 15 carbon atoms, and s represents aninteger between 0 and 10.

Specific examples of a group represented by formula (12-1) may include atert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, atert-amyloxycarbonyl group, a tert-amyloxycarbonylmethyl group, a1,1-diethylpropyloxycarbonyl group, a 1,1-diethylpropyloxycarbonylmethylgroup, a 1-ethylcyclopentyloxycarbonyl group, a1-ethylcyclopentyloxycarbonylmethyl group, a1-ethyl-2-cyclopentenyloxycarbonyl group, a1-ethyl-2-cyclopentenyloxycarbonylmethyl group, a 1-ethoxycarbonylmethylgroup, a 2-tetrahydropyranyloxycarbonylmethyl group, and a2-tetrahydrofuranyloxycarbonylmethyl group.

In formula (12-2), each of R¹⁰² and R¹⁰³ independently represents ahydrogen atom, or a linear, branched, or cyclic alkyl group having 1 to18 carbon atoms, and preferably 1 to 10 carbon atoms. Specific examplesof such an alkyl group may include a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group,a tert-butyl group, a cyclopentyl group, a cyclohexyl group, a2-ethylcyclohexyl group, and an n-octyl group.

In formula (12-2), R¹⁰⁴ represents a monovalent hydrocarbon group having1 to 20 carbon atoms, and preferably 1 to 10 carbon atoms, that maycontain a heteroatom such as an oxygen atom. Examples of R¹⁰⁴ mayinclude a linear, branched, or cyclic alkyl group, and a linear,branched, or cyclic alkyl group, several hydrogen atoms of which aresubstituted with a hydroxyl group, an alkoxy group, an oxo group, anamino group, an alkylamino group, or the like.

In addition, R¹⁰² and R¹⁰³, R¹⁰² and R¹⁰⁴, or R¹⁰³ and R¹⁰⁴, may bind toeach other, so as to form a ring. In this case, each of R¹⁰², R¹⁰³, andR¹⁰⁴ is an alkylene group having 1 to 18 carbon atoms, and preferably 1to 10 carbon atoms, that may contain a heteroatom such as an oxygenatom.

Specific examples of a group represented by formula (12-2) may include atetrahydrofuran-2-yl group, a 2-methyltetrahydrofuran-2-yl group, atetrahydropyran-2-yl group, a 2-methyltetrahydropyran-2-yl group, andgroups represented by the following formulas:

Of these, an ethoxyethyl group, a butoxyethyl group, and an ethoxypropylgroup are preferable as groups represented by formula (12-2).

In formula (12-3), each of R¹⁰⁵, R¹⁰⁶, and R¹⁰⁷ independently representsa linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms,and preferably 1 to 10 carbon atoms. Examples of such an alkyl group arethe same as those of R¹⁰² and R¹⁰³ in formula (12-2).

Moreover, R¹⁰⁵ and R¹⁰⁶, R¹⁰⁵ and R¹⁰⁷, or R¹⁰⁶ and R¹⁰⁷, may bind toeach other, so as to form a ring.

Specific examples of a group represented by formula (12-3) may include atert-butyl group, a tert-amyl group, a triethylcarbyl group, a1-methylcyclohexyl group, a 1-ethylcyclopentyl group, a 1-ethylnorbornylgroup, a 2-(2-methyl)adamantyl group, a 2-(2-ethyl)adamantyl group, a1,1,1,3,3,3-hexafluoro-2-methyl-isopropyl group, and a1,1,1,3,3,3-hexafluoro-2-cyclohexyl-isopropyl group. Furthermore, groupsrepresented by the following formulas (13-1) to (13-17) are alsoincluded.

(wherein, each of R²⁴, R²⁵¹, and R²⁵² independently represents a linear,branched, or cyclic alkyl group having 1 to 6 carbon atoms, each of R²⁶and R²⁷ independently represents a hydrogen atom, a monovalenthydrocarbon group that may contain a heteroatom, or a monovalenthydrocarbon group that may be mediated by a heteroatom, wherein, in sucha case, examples of a heteroatom may include an oxygen atom, a sulfuratom, and a nitrogen atom, and such a heteroatom may be contained- ormediated in the form of —OH, —OR²⁸, —O—, —S—, —S(═O)—, —NH₂, —NHR²⁸,—N(R²⁸)₂, —NH—, —NR²⁸—, or the like, and R²⁸ represents a linear,branched, or cyclic alkyl group having 1 to 10 carbon atoms.)

Specific examples of R²⁴, R²⁵¹, and R²⁵² may include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, asec-butyl group, an n-pentyl group, an n-hexyl group, a cyclopropylgroup, a cyclopropylmethyl group, a cyclobutyl group, a cyclopentylgroup, and a cyclohexyl group.

Examples of R²⁶ and R²⁷ may include a linear, branched, or cyclic alkylgroup, a hydroxyalkyl group, an alkoxy group, an alkoxyalkyl group, aswell as a hydrogen atom. Specific examples may include a methyl group, ahydroxymethyl group, an ethyl group, a hydroxyethyl group, an n-propylgroup, an isopropyl group, an n-butyl group, a sec-butyl group, ann-pentyl group, an n-hexyl group, a methoxy group, a methoxymethoxygroup, an ethoxy group, and a tert-butoxy group.

In formula (12-4), each of R¹⁰⁸, R¹⁰⁹, and R¹¹⁰ independently representsa hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group,or an aryl group.

An alkyl group may be either linear or branched. The number of carbonatoms contained in such an alkyl group is not particularly limited. Itis preferably between 1 and 18, and more preferably between 1 and 10.The number of carbon atoms contained in a cycloalkyl group is notparticularly limited. It is preferably between 1 and 18, and morepreferably between 1 and 10. Examples of such an alkyl group andcycloalkyl group are the same as those of R¹⁰⁵, R¹⁰⁶, and R¹⁰⁷ informula (12-3).

The number of carbon atoms contained in an alkenyl group is notparticularly limited. It is preferably between 2 and 4. Examples of suchan alkenyl group may include a vinyl group, a propenyl group, an allylgroup, and a butenyl group.

The number of carbon atoms contained in an aryl group is notparticularly limited. It is preferably between 6 and 14. Examples ofsuch an aryl group may include a phenyl group, a xylyl group, a toluylgroup, a cumenyl group, a naphthyl group, and an anthracenyl group.

In addition, R¹⁰⁸ and R¹⁰⁹, R¹⁰⁸ and R¹¹⁰, or R¹⁰⁹ and R¹¹⁰, may bind toeach other, so as to form a ring. Examples of groups that form such aring are the same as those of R¹⁰⁵ and R¹⁰⁶, R¹⁰⁵ and R¹⁰⁷, or R¹⁰⁶ andR¹⁰⁷ in formula (12-3).

In formula (12-4), A¹⁰¹ represents a divalent aromatic hydrocarbon groupthat may have a monocyclic or polycyclic substituent. The number ofcarbon atoms contained in this divalent aromatic hydrocarbon group isnot particularly limited. It is preferably between 6 and 14. Examples ofsuch a divalent aromatic hydrocarbon group may include a phenyl group, axylyl group, a toluyl group, a cumenyl group, a naphthyl group, and ananthracenyl group. Examples of a substituent may include: alkyl groupssuch as a hydroxyl group, a halogen atom (fluorine, chlorine, bromine,iodine), a nitro group, a cyano group, alkyl groups such as a methylgroup, an ethyl group, a propyl group, an isopropyl group, an n-butylgroup, a sec-butyl group, an n-pentyl group, an n-hexyl group, acyclopropyl group, a cyclopropylmethyl group, a cyclobutyl group, acyclopentyl group, or a cyclohexyl group; alkoxy groups such as amethoxy group, an ethoxy group, a hydroxyethoxy group, a propoxy group,a hydroxypropoxy group, an n-butoxy group, an isobutoxy group, asec-butoxy group, or a t-butoxy group; alkoxycarbonyl groups such as amethoxycarbonyl group or an ethoxycarbonyl group; aralkyl groups such asa benzyl group, a phenethyl group, or a cumyl group; acyl groups such asan aralkyloxy group, a formyl group, an acetyl group, a butyryl group, abenzoyl group, a cyanamyl group, or valeryl group; acyloxy groups suchas a butyryloxy group; alkenyloxy groups such as the aforementionedalkenyl group, a vinyloxy group, a propenyloxy group, an allyloxy group,or a butenyloxy group; aryloxy groups such as the aforementioned arylgroup or a phenoxy group; and aryloxycarbonyl groups such as abenzoyloxy group.

In formula (12-5), each of R¹¹¹ and R¹¹² independently represents ahydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, andan aryl group. In formula (12-5), examples of R¹¹¹ and R¹¹² are the sameas those of R¹⁰⁸, R¹⁰⁹ and R¹¹⁰ in formula (12-4), and preferredexamples are also the same as those of R¹⁰⁸, R¹⁰⁹ and R¹¹⁰.

In formula (12-5), R¹¹³ represents an alkyl group or an aryl group.

An alkyl group may be either linear or branched. The number of carbonatoms contained in such an alkyl group is not particularly limited. Itis preferably between 1 and 20, and more preferably between 1 and 10.Examples of such an alkyl group are the same as those of R¹⁰² and R¹⁰³in formula (12-2).

The number of carbon atoms contained in an aryl group is notparticularly limited. It is preferably between 6 and 14. Examples ofsuch an aryl group may include a phenyl group, a xylyl group, a toluylgroup, a cumenyl group, a naphthyl group, and an anthracenyl group.

In addition, R¹¹¹ and R¹¹², R¹¹¹ and R¹¹³, or R¹¹² and R¹¹³, may bind toeach other, so as to form a ring. In such a case, each of R¹¹¹, R¹¹²,and R¹¹³ is an alkylene group having preferably 1 to 18 carbon atoms,and more preferably 1 to 10 carbon atoms, that may contain a heteroatomsuch as an oxygen atom. Examples of groups that form such a ring are thesame as those of R¹⁰² and R¹⁰³, R¹⁰² and R¹⁰⁴, or R¹⁰³ and R¹⁰⁴ informula (12-2).

In formula (12-5), A¹⁰² represents a divalent aromatic hydrocarbon groupthat may have a monocyclic or polycyclic substituent. In formula (12-5),examples of A¹⁰² are the same as those of A¹⁰¹ in formula (12-4).Preferred examples of A¹⁰² are also the same as those of A¹⁰¹ in formula(12-4).

In formula (12-6), each of R¹¹⁴, R¹¹⁵, and R¹¹⁶ independently representsa hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group,or an aryl group. In formula (12-6), examples of such R¹¹⁴, R¹¹⁵, andR¹¹⁶ are the same as those of R¹⁰⁸, R¹⁰⁹, and R¹¹⁰ in formula (12-4).Preferred examples of R¹¹⁴, R¹¹⁵, and R¹¹⁶ are also the same as those ofR¹⁰⁸, R¹⁰⁹, and R¹¹⁰ in formula (12-4).

In formula (12-6), A¹⁰³ represents a divalent aromatic hydrocarbon groupthat may have a monocyclic or polycyclic substituent. In formula (12-6),examples of A¹⁰³ are the same as those of A¹⁰¹ in formula (12-4).Preferred examples of A¹⁰³ are also the same as those of A¹⁰¹ in formula(12-4).

In formula (12-7), each of R¹¹⁷, R¹¹⁸, and R¹¹⁹ independently representsa hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group,or an aryl group. In formula (12-7), A¹⁰⁴ represents a divalent aromatichydrocarbon group that may have a monocyclic or polycyclic substituent.In formula (12-7), examples of R¹¹⁷, R¹¹⁸, R¹¹⁹, and A¹⁰⁴ are the sameas those of R¹⁰⁸, R¹⁰⁹, R¹¹⁰, and A¹⁰¹ in formula (12-4). Preferredexamples of R¹¹⁷, R¹¹⁸, R¹¹⁹, and A¹⁰³ are also the same as those ofR¹⁰⁸, R¹⁰⁹, R¹¹⁰, and A¹⁰¹ in formula (12-4).

In formula (12-8), each of R¹²⁰ and R¹²¹ independently represents ahydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, oran aryl group. In formula (12-8), R¹²² represents an alkyl group or anaryl group. In formula (12-8), A¹⁰⁵ represents a divalent aromatichydrocarbon group that may have a monocyclic or polycyclic substituent.In formula (12-8), examples of R¹²⁰, R¹²¹, R¹²², and A¹⁰⁵ are the sameas those of R¹¹¹, R¹¹², R¹¹³, and A¹⁰² in formula (12-5). Preferredexamples of R¹²⁰, R¹²¹, R¹²², and A¹⁰⁵ are also the same as those ofR¹¹¹, R¹¹², R¹¹³, and A¹⁰² in formula (12-5).

In formula (12-9), each of R¹²³, R¹²⁴, and R¹²⁵ independently representsa hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group,or an aryl group. In formula (12-9), A¹⁰⁶ represents a divalent aromatichydrocarbon group that may have a monocyclic or polycyclic substituent.In formula (12-9), examples of R¹²³, R¹²⁴, R¹²⁵, and A¹⁰⁶ are the sameas those of R¹¹⁴, R¹¹⁵, R¹¹⁶, and A¹⁰³ in formula (12-6). Preferredexamples of R¹²³, R¹²⁴, R¹²⁵, and A¹⁰⁶ are also the same as those ofR¹¹⁴, R¹¹⁵, R¹¹⁶ and A¹⁰³ in formula (12-6).

An acid-dissociable group preferably has an alicyclic skeleton in orderto achieve high dry etching resistance required for resists.Specifically, the groups represented by the above formulas (13-1) to(13-17), which were exemplified for the group represented by formula(12-3), are preferable as such acid-dissociable groups.

Examples of a preferred constitutional unit having an acid-dissociablegroup may include constitutional units represented by the followingformulas (7-1) to (7-4):

(wherein, in formulas (7-1) to (7-4), each of R⁸¹, R⁸², R⁸³, and R⁸⁴represents a hydrogen atom or a methyl group.)

Of these, the constitutional unit represented by the above formula (7-3)and the constitutional unit represented by the above formula (7-4) aremore preferable because they achieve high dry etching resistancerequired for resists.

The constitutional units represented by the above formulas (7-1) to(7-4) are obtained by copolymerization of monomers represented by thefollowing formulas (8-1) to (8-4):

(wherein, in formulas (8-1) to (8-4), each of R⁸¹, R⁸², R⁸³, and R⁸⁴represents a hydrogen atom or a methyl group.)

As a constitutional unit having an acid-dissociable group, aconstitutional unit having an alicyclic skeleton is preferable becauseit achieves high dry etching resistance required for resists. Such aconstitutional unit having an alicyclic skeleton is a constitutionalunit having at least one cyclic hydrocarbon group. Such a constitutionalunit is usually a group wherein a cyclic hydrocarbon group isdissociated by the action of acid.

As such a constitutional unit having an acid-dissociable group, theconstitutional unit represented by the above formula (3-1-1), theconstitutional unit represented by the above formula (3-2-1), and theconstitutional unit represented by the above formula (3-3-1) areparticularly preferable because they achieve high dry etching resistancerequired for resists.

In terms of sensitivity and resolution, preferred examples of R¹ informula (3-1-1) may include a methyl group, an ethyl group, and anisopropyl group.

In terms of high dry etching resistance, n1 in formula (3-1-1) ispreferably 0.

In terms of sensitivity and resolution, preferred examples of R² and R³in formula (3-2-1) may include a methyl group, an ethyl group, and anisopropyl group.

In terms of high dry etching resistance, n2 in formula (3-2-1) ispreferably 0.

In terms of sensitivity and resolution, preferred examples of R⁴ informula (3-3-1) may include a methyl group, an ethyl group, and anisopropyl group.

In terms of high dry etching resistance, n3 in formula (3-3-1) ispreferably 0.

In terms of high dry etching resistance, q in formula (3-3-1) ispreferably 1.

In order to introduce a constitutional unit having an acid-dissociablegroup into a polymer, a monomer having an acid-dissociable group may becopolymerized. Such a monomer having an acid-dissociable group may beused alone or in combination, as necessary.

Specific examples of a monomer having an acid-dissociable group mayinclude monomers represented by the following formulas (9-1) to (9-18)and (9-23). In formulas (9-1) to (9-18) and (9-23), R represents ahydrogen atom or a methyl group.

Of these, as a monomer having an acid-dissociable group, the monomerrepresented by the above formula (9-1), the monomer represented by theabove formula (9-2), the monomer represented by the above formula (9-5),the monomer represented by the above formula (9-16), the monomerrepresented by the above formula (9-23), geometric isomers thereof, andoptical isomers are more preferable in terms of sensitivity andresolution. Moreover, the monomer represented by the above formula (9-1)and the monomer represented by the above formula (9-2) are particularlypreferable. Although the monomer represented by the above formula (9-23)is not a constitutional unit having an alicyclic skeleton, it ispreferable because it can achieve high sensitivity and high resolution.

Moreover, a constitutional unit having an acid-dissociable group mayalso include those represented by the following formulas:

(wherein R⁸⁰ represents an acid-dissociable group.)

A constitutional unit having a lactone skeleton will be described.

When a constitutional unit having a lactone skeleton has a protectinggroup that is dissociated by the action of acid, it has superiorsensitivity. In addition, when a constitutional unit having a lactoneskeleton has a high carbon density, that is, when the ratio of thenumber of carbon atoms to the total number of atoms in the aboveconstitutional unit is high, it has superior dry etching resistance.

In the present invention, the constitutional unit having a lactoneskeleton is at least one selected from the group consisting of thoserepresented by the above formulas (4-1), (4-2), (4-3), (4-5), (4-6), and(4-10). It is preferable not to contain other types of constitutionalunits having a lactone skeleton.

As a constitutional unit having a lactone skeleton, the constitutionalunit represented by the above formula (4-1), the constitutional unitrepresented by the above formula (4-2), the constitutional unitrepresented by the above formula (4-3), the constitutional unitrepresented by the above formula (4-5), the constitutional unitrepresented by the above formula (4-6), and the constitutional unitrepresented by the above formula (4-10), are preferable in terms ofsensitivity and dry etching resistance.

In formula (4-1), n5 is preferably 0 in terms of high dry etchingresistance.

In formula (4-1), m is preferably 1 in terms of sensitivity andresolution.

In formula (4-2), each of A¹ and A² is preferably —O— in terms of highsolubility in organic solvents.

In formula (4-2), each of R²⁰¹ and R²⁰² is preferably a hydrogen atom, amethyl group, an ethyl group, or an isopropyl group in terms of highsolubility in organic solvents.

In formula (4-2), n6 is preferably 0 in terms of high dry etchingresistance.

In formula (4-3), each of A³ and A⁴ is preferably —CH₂— in terms of highdry etching resistance, and it is preferably —O— in terms of highsolubility in organic solvents.

In formula (4-3), each of R²⁰³ and R²⁰⁴ is preferably a hydrogen atom, amethyl group, an ethyl group, or an isopropyl group in terms of highsolubility in organic solvents.

In formula (4-3), n7 is preferably 0 in terms of high dry etchingresistance.

In formula (4-5), each of R⁸ and R⁹ is preferably a methyl group, anethyl group, or an isopropyl group in terms of sensitivity andresolution.

In formula (4-5), each of R⁵², R⁶², and R⁷² is preferably a hydrogenatom in terms of high solubility in organic solvents.

With regard to Y¹², Y²², and Y³² in formula (4-5), one is preferably—CO—O— and the remaining two are —CH₂—, in terms of high adhesiveness tothe metal surface or the like.

In formula (4-5), n9 is preferably 0 in terms of high dry etchingresistance.

In formula (4-6), R¹⁰ is preferably a methyl group, an ethyl group, oran isopropyl group in terms of sensitivity and resolution.

In formula (4-6), each of R⁵³, R⁶³, and R⁷³ is preferably a hydrogenatom in terms of high solubility in organic solvents.

With regard to Y¹³, Y²³, and Y³³ in formula (4-6), one is preferably—CO—O— and the remaining two are —CH₂—, in terms of high adhesiveness tothe metal surface or the like.

In formula (4-6), n10 is preferably 0 in terms of high dry etchingresistance.

In formula (4-10), each of R⁹¹, R⁹², R⁹³, and R⁹⁴ is preferably ahydrogen atom or a methyl group in terms of high solubility in organicsolvents.

In formula (4-10), m1 is preferably 1 in terms of sensitivity andresolution.

As a constitutional unit having a lactone skeleton, the constitutionalunit represented by the above formula (4-1), the constitutional unitrepresented by the above formula (4-2), the constitutional unitrepresented by the above formula (4-3), and the constitutional unitrepresented by the above formula (4-10), are more preferable in terms ofhigh solubility in organic solvents and inexpensiveness. In order toachieve high sensitivity and inexpensiveness, the constitutional unitrepresented by the above formula (4-1) is particularly preferable. Inorder to achieve high dry etching resistance, the constitutional unitrepresented by the above formula (4-2) and the constitutional unitrepresented by the above formula (4-3) are particularly preferable. Inorder to achieve excellent heat stability and inexpensiveness, theconstitutional unit represented by the above formula (4-10) isparticularly preferable.

In order to introduce a constitutional unit having a lactone skeletoninto a polymer, a monomer having a lactone skeleton may becopolymerized. Such a monomer having a lactone skeleton may be usedalone or in combination, as necessary.

Examples of a monomer having a lactone skeleton may include a(meth)acrylic acid derivative having a δ-valerolactone ring, a(meth)acrylic acid derivative having a γ-butyrolactone ring, a(meth)acrylic acid derivative having polycyclic lactone, and aderivative having a substituent on the lactone ring of these compounds.

Specific examples of a monomer having a lactone skeleton may includemonomers represented by formulas (10-1) to (10-20), (10-22) to (10-24),and (10-41) indicated below. In formulas (10-1) to (10-20), (10-22) to(10-24), and (10-41), R represents a hydrogen atom or a methyl group.

As a monomer having a lactone skeleton, the monomer represented by theabove formula (10-1), the monomer represented by the above formula(10-2), the monomer represented by the above formula (10-41), and anoptical isomer thereof, are more preferable in terms of sensitivity. Interms of dry etching resistance, the monomer represented by the aboveformula (10-6), the monomer represented by the above formula (10-10),the monomer represented by the above formula (10-14), the monomerrepresented by the above formula (10-18), a geometric isomer thereof,and an optical isomer thereof, are more preferable. In terms ofsolubility in resist solvents, the monomer represented by the aboveformula (10-7), the monomer represented by the above formula (10-11),the monomer represented by the above formula (10-15), the monomerrepresented by the above formula (10-19), a geometric isomer thereof,and an optical isomer thereof, are more preferable.

Further examples of a monomer having a lactone skeleton may includemonomers represented by formulas (10-25) to (10-40) and (10-44) to(10-50) indicated below. In formulas (10-25) to (10-40) and (10-44) to(10-50), R represents a hydrogen atom or a methyl group.

Of these, in terms of high solubility in organic solvents, the monomerrepresented by the above formula (10-25), a geometric isomer thereof,and an optical isomer thereof, are preferable.

Furthermore, examples of a monomer having a lactone skeleton may alsoinclude monomers represented by formulas (10-51) to (10-60) indicatedbelow.

Of these, in terms of high solubility in organic solvents, the monomerrepresented by the above formula (10-55), the monomer represented by theabove formula (10-56), the monomer represented by the above formula(10-57), and the monomer represented by the above formula (10-58), arepreferable. The monomer represented by the above formula (10-58) is morepreferable.

The resist polymer of the present invention may further compriseconstitutional units other than those as described above. That is tosay, the resist polymer of the present invention may be formed bycopolymerization of copolymerizable monomers, other than a (meth)acrylicacid ester derivative containing a cyano group represented by the aboveformula (5), a monomer having an acid-dissociable group, and a monomerhaving a lactone skeleton represented by at least one selected from thegroup consisting of the above formulas (4-1), (4-2), (4-3), (4-5),(4-6), and (4-10).

For example, the resist polymer of the present invention may comprise aconstitutional unit having an alicyclic skeleton that does not have anacid-dissociable group. Such a constitutional unit having an alicyclicskeleton has at least one cyclic hydrocarbon group. Such aconstitutional unit having an alicyclic skeleton may be used alone or incombination.

A resist polymer, which contains a constitutional unit having analicyclic skeleton, is excellent in terms of dry etching resistance.Moreover, when such a constitutional unit has a hydroxyl group, asuperior resist pattern can be obtained.

As a constitutional unit having an alicyclic skeleton, a constitutionalunit represented by the following formula (3-1-2) and a constitutionalunit represented by the following formula (3-4) are preferable becausethey have high dry etching resistance required for resists:

(wherein, in formula (3-1-2), R³¹ represents a hydrogen atom or a methylgroup; R¹¹ represents a hydrogen atom; X¹ represents a linear orbranched alkyl group having 1 to 6 carbon atoms that may have, as asubstituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, a cyano group,and an amino group, a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, or an amino group; and n1 represents an integer between 0 and 4,and when n1 is 2 or greater, X¹ may be a plurality of different groups,and

wherein, in formula (3-4), R³⁴ represents a hydrogen atom or a methylgroup; X⁴ represents a linear or branched alkyl group having 1 to 6carbon atoms that may have, as a substituent, at least one selected fromthe group consisting of a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, and an amino group, a hydroxy group, a carboxy group, an acylgroup having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbonatoms, a carboxy group that is esterified with alcohol having 1 to 6carbon atoms, or an amino group; and n4 represents an integer between 0and 4, and when n4 is 2 or greater, X⁴ may be a plurality of differentgroups.)

In formula (3-1-2) and formula (3-4), positions substituted with X¹ andX⁴ may be any positions in the cyclic structure.

In formula (3-1-2), n1 is preferably 0 in order to achieve high dryetching resistance, and it is preferably 1 in order to achieve a goodresist pattern.

When n1 is 1 or greater, X¹ is preferably a hydroxy group in order toachieve a good resist pattern.

In formula (3-4), n4 is preferably 0 in order to achieve high dryetching resistance, and it is preferably 1 in order to achieve a goodresist pattern.

When n4 is 1 or greater, X⁴ is preferably a hydroxy group in order toachieve a good resist pattern.

In order to introduce a constitutional unit having an alicyclic skeletoninto a polymer, a monomer having an alicyclic skeleton may becopolymerized. Such a monomer having an alicyclic skeleton may be usedalone or in combination, as necessary.

Preferred examples of a monomer having an alicyclic skeleton may includecyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl(meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentadienyl(meth)acrylate, and derivatives having substituents on cyclichydrocarbon groups of these compounds.

Specific examples of a monomer having an alicyclic skeleton may includemonomers represented by formulas (9-19) to (9-22) indicated below. Informulas (9-19) to (9-22), R represents a hydrogen atom or a methylgroup.

Moreover, examples of copolymerizable monomers other than those asdescribed above may include:

(meth)acrylic acid esters with a linear or branched structure, such asmethyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, butyl(meth)acrylate, isobutyl (meth)acrylate, methoxymethyl (meth)acrylate,n-propoxyethyl (meth)acrylate, i-propoxyethyl (meth)acrylate,n-butoxyethyl (meth)acrylate, i-butoxyethyl (meth)acrylate,t-butoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate,3-hydroxypropyl (meth)acrylate, 2-hydroxy-n-propyl (meth)acrylate,4-hydroxy-n-butyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate,1-ethoxyethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate,2,2,3,3-tetrafluoro-n-propyl (meth)acrylate,2,2,3,3,3-pentafluoro-n-propyl (meth)acrylate, methylα-(tri)fluoromethylacrylate, ethyl α-(tri)fluoromethylacrylate,2-ethylhexyl α-(tri)fluoromethylacrylate, n-propylα-(tri)fluoromethylacrylate, i-propyl α-(tri)fluoromethylacrylate,n-butyl α-(tri)fluoromethylacrylate, i-butylα-(tri)fluoromethylacrylate, t-butyl α-(tri)fluoromethylacrylate,methoxymethyl α-(tri)fluoromethylacrylate, ethoxyethylα-(tri)fluoromethylacrylate, n-propoxyethyl α-(tri)fluoromethylacrylate,i-propoxyethyl α-(tri)fluoromethylacrylate, n-butoxyethylα-(tri)fluoromethylacrylate, i-butoxyethyl α-(tri)fluoromethylacrylate,or t-butoxyethyl α-(tri)fluoromethylacrylate;

aromatic alkenyl compounds, such as styrene, α-methylstyrene,vinyltoluene, p-hydroxystyrene, p-t-butoxycarbonylhydroxystyrene,3,5-di-t-butyl-4-hydroxystyrene, 3,5-dimethyl-4-hydroxystyrene,p-t-perfluorobutylstyrene, or p-(2-hydroxy-i-propyl)styrene;

unsaturated carboxylic acids and carboxylic anhydrides, such as acrylicacid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, oritaconic anhydride; and

ethylene, propylene, norbornene, tetrafluoroethylene, acrylamide,N-methylacrylamide, N,N-dimethylacrylamide, vinyl chloride, vinylfluoride, vinylidene fluoride, tetrafluoroethylene, andvinylpyrrolidone. These monomers may be used alone or in combination, asnecessary.

Other monomers may be used within a range that does not significantlyimpair the effects of the present invention. In general, other monomersmay preferably be used within a range of 20% or less by mole based onthe total monomer components.

In the resist polymer of the present invention, as a constitutional unitrepresented by the above formula (1), at least one selected from thegroup consisting of the constitutional units represented by the aboveformula (2) and (1-1) is preferable. As a constitutional unit having anacid-dissociable group, at least one selected from the group consistingof the constitutional units represented by the above formulas (3-1-1),(3-3-1), and (3-5) is preferable. As a constitutional unit having alactone skeleton, at least one selected from the group consisting of theconstitutional units represented by the above formulas (4-2), (4-3),(4-7), (4-8), (4-9), and (4-11) is preferable.

Taking into consideration resist pattern, suppression of line edgeroughness and microgels, sensitivity, resolution, adhesiveness to themetal surface, and high solubility in organic solvents, a polymer, whichcomprises at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (2) and (1-1), atleast one constitutional unit selected from the group consisting ofthose represented by the above formulas (3-1-1), (3-3-1), and (3-5), andat least one constitutional unit represented by formula (4-7) indicatedbelow, is preferable as the resist polymer of the present invention.

(wherein, in formula (4-7), R⁴⁷ represents a hydrogen atom or a methylgroup.)

In this polymer, at least one constitutional unit selected from thegroup consisting of those represented by the above formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5), and the constitutional unit represented by the above formula(4-7), are not necessarily all the same, but may be a mixture of two ormore kinds thereof, as long as they can be represented by generalformulas as described above. In addition, in this polymer, eachconstitutional unit may have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

The total ratio of at least one constitutional unit selected from thoserepresented by the above formulas (2) and (1-1) in the polymer ispreferably between 5% and 30% by mole, in terms of resist pattern andsuppression of line edge roughness and microgels. In addition, the totalratio of at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5) in the polymer is preferably between 30% and 60% by mole, interms of sensitivity and resolution. Moreover, the total ratio of theconstitutional unit represented by the above formula (4-7) in thepolymer is preferably between 30% and 60% by mole, in terms ofadhesiveness to the metal surface or the like and high solubility inorganic solvents.

As the resist polymer of the present invention, a polymer, whichcomprises at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (2) and (1-1), atleast one constitutional unit selected from the group consisting ofthose represented by the above formulas (3-1-1), (3-3-1), and (3-5), andat least one constitutional unit represented by formula (4-8) indicatedbelow, is preferable, in terms of resist pattern, suppression of lineedge roughness and microgels, sensitivity, resolution, adhesiveness tothe metal surface, and high solubility in organic solvents.

(wherein, in formula (4-8), R⁴⁸ represents a hydrogen atom or a methylgroup.)

In this polymer, at least one constitutional unit selected from thegroup consisting of those represented by the above formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5), and the constitutional unit represented by the above formula(4-8), are not necessarily all the same, but may be a mixture of two ormore kinds thereof, as long as they can be represented by generalformulas as described above. In addition, in this polymer, eachconstitutional unit may have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

The total ratio of at least one constitutional unit selected from thoserepresented by the above formulas (2) and (1-1) in the polymer ispreferably between 5% and 30% by mole, in terms of resist pattern andsuppression of line edge roughness and microgels. In addition, the totalratio of at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5) in the polymer is preferably between 30% and 60% by mole, interms of sensitivity and resolution. Moreover, the total ratio of theconstitutional unit represented by the above formula (4-8) in thepolymer is preferably between 30% and 60% by mole, in terms ofadhesiveness to the metal surface or the like and high solubility inorganic solvents.

As the resist polymer of the present invention, a polymer, whichcomprises at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (2) and (1-1), atleast one constitutional unit selected from the group consisting ofthose represented by the above formulas (3-1-1), (3-3-1), and (3-5), andat least one constitutional unit represented by formula (4-11) indicatedbelow, is preferable, in terms of resist pattern, suppression of lineedge roughness and microgels, sensitivity, resolution, adhesiveness tothe metal surface, and high solubility in organic solvents.

(wherein, in formula (4-11), R⁴¹¹ represents a hydrogen atom or a methylgroup.)

In this polymer, at least one constitutional unit selected from thegroup consisting of those represented by the above formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1);and (3-5), and the constitutional unit represented by the above formula(4-11), are not necessarily all the same, but may be a mixture of two ormore kinds thereof, as long as they can be represented by generalformulas as described above. In addition, in this polymer, eachconstitutional unit may have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

The total ratio of at least one constitutional unit selected from thoserepresented by the above formulas (2) and (1-1) in the polymer ispreferably between 5% and 30% by mole, in terms of resist pattern andsuppression of line edge roughness and microgels. In addition, the totalratio of at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5) in the polymer is preferably between 30% and 60% by mole, interms of sensitivity and resolution. Moreover, the total ratio of theconstitutional unit represented by the above formula (4-11) in thepolymer is preferably between 30% and 60% by mole, in terms ofadhesiveness to the metal surface or the like and high solubility inorganic solvents.

As the resist polymer of the present invention, a polymer, whichcomprises at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (2) and (1-1), atleast one constitutional unit selected from the group consisting ofthose represented by the above formulas (3-1-1), (3-3-1), and (3-5), andat least one constitutional unit represented by formula (4-9) indicatedbelow, is preferable, in terms of resist pattern, suppression of lineedge roughness and microgels, sensitivity, resolution, adhesiveness tothe metal surface, and high solubility in organic solvents.

(wherein, in formula (4-9), R⁴⁹ represents a hydrogen atom or a methylgroup.) In this polymer, at least one constitutional unit selected fromthe group consisting of those represented by the above formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5), and the constitutional unit represented by the above formula(4-9), are not necessarily all the same, but may be a mixture of two ormore kinds thereof, as long as they can be represented by generalformulas as described above. In addition, in this polymer, eachconstitutional unit may have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

The total ratio of at least one constitutional unit selected from thoserepresented by the above formulas (2) and (1-1) in the polymer ispreferably between 5% and 30% by mole, in terms of resist pattern andsuppression of line edge roughness and microgels. In addition, the totalratio of at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5) in the polymer is preferably between 30% and 60% by mole, interms of sensitivity and resolution. Moreover, the total ratio of theconstitutional unit represented by the above formula (4-9) in thepolymer is preferably between 30% and 60% by mole, in terms ofadhesiveness to the metal surface or the like and high solubility inorganic solvents.

As the resist polymer of the present invention, a polymer, whichcomprises at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (2) and (1-1), atleast one constitutional unit selected from the group consisting ofthose represented by the above formulas (3-1-1), (3-3-1), and (3-5), andat least one constitutional unit selected from the group consisting ofthose represented by the above formulas (4-2) and (4-3), is preferable,in terms of resist pattern, suppression of line edge roughness andmicrogels, sensitivity, resolution, adhesiveness to the metal surface,and high dry etching resistance.

In this polymer, at least one constitutional unit selected from thegroup consisting of those represented by the above formulas (2) and(1-1), at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5), and at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (4-2) and (4-3),are not necessarily all the same, but may be a mixture of two or morekinds thereof, as long as they can be represented by general formulas asdescribed above. In addition, in this polymer, each constitutional unitmay have any given sequence. Accordingly, this polymer may be a randomcopolymer, an alternating copolymer, or a block copolymer.

The total ratio of at least one constitutional unit selected from thoserepresented by the above formulas (2) and (1-1) in the polymer ispreferably between 5% and 30% by mole, in terms of resist pattern andsuppression of line edge roughness and microgels. In addition, the totalratio of at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-3-1),and (3-5) in the polymer is preferably between 30% and 60% by mole, interms of sensitivity and resolution. Moreover, the total ratio of atleast one constitutional unit selected from the group consisting ofthose represented by the above formulas (4-2) and (4-3) in the polymeris preferably between 30% and 60% by mole, in terms of adhesiveness tothe metal surface or the like and high dry etching resistance.

The mass average molecular weight of the resist polymer of the presentinvention is not particularly limited. In terms of dry etchingresistance and resist pattern, it is preferably 1,000 or greater, morepreferably 2,000 or greater, and particularly preferably 4,000 orgreater. In addition, in terms of solubility in a resist solution andresolution, the mass average molecular weight of the resist polymer ofthe present invention is preferably 100,000 or less, more preferably50,000 or less, and particularly preferably 30,000 or less. Moreover,depending on the type of a constitutional unit having a lactone skeletoncontained in the resist polymer of the present invention, when thepolymer of the present invention contains a constitutional unit derivedfrom 2-exo-methacryloyloxy-4-oxatricyclo[4.2.1.0^(3,7)]nonan-5-one(which may also be referred to as OTNMA) for example, the mass averagemolecular weight thereof is more preferably 8,000 or less, in terms ofsolubility in a resist solution and resist pattern.

As stated above, in recent years, a resist polymer, which can achieve auniform resist pattern size, having a small degree of deviation on thesurface of a large substrate with a diameter of 300 mm or greater and asmall degree of PEB temperature dependence, has been required.

From such a viewpoint, the mass average molecular weight of the resistpolymer of the present invention is preferably between 5,000 and 8,000.More preferably, the upper limit thereof is 7,000 or less.

Moreover, from such a viewpoint, as the resist polymer of the presentinvention, a polymer, which comprises at least one constitutional unitrepresented by the above formula (1), at least one constitutional unitselected from the group consisting of those represented by the aboveformulas (3-1-1), (3-2-1), and (3-3-1), and at least one constitutionalunit selected from the group consisting of those represented by theabove formulas (4-7) and (4-8), is preferable. Such a polymer exhibitsparticularly small PEB temperature dependence in ordinary lithography,and a uniform resist pattern size with a particularly small degree ofvariation can be obtained even on the surface of a large substrate witha diameter of 300 mm or greater.

In this polymer, the constitutional unit represented by the aboveformula (1), at least one constitutional unit selected from the groupconsisting of those represented by the above formulas (3-1-1), (3-2-1),and (3-3-1), and at least one constitutional unit selected from thegroup consisting of those represented by the above formulas (4-7) and(4-8), are not necessarily all the same, but may be a mixture of two ormore kinds thereof, as long as they can be represented by generalformulas as described above. In addition, in this polymer, eachconstitutional unit may have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

The total ratio of the constitutional unit represented by the aboveformula (1) in the polymer is preferably between 5% and 30% by mole. Inaddition, the total ratio of at least one constitutional unit selectedfrom the group consisting of those represented by the above formulas(3-1-1), (3-2-1), and (3-3-1) in the polymer is preferably between 30%and 60% by mole. Moreover, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by the above formulas (4-7) and (4-8) in the polymer ispreferably between 30% and 60% by mole. By adjusting the ratios ofconstitutional units within the above ranges, higher effects can beobtained from the present invention.

Among others, a polymer comprising at least one constitutional unitrepresented by the above formula (2), at least one constitutional unitrepresented by the above formula (3-1-1), and at least oneconstitutional unit represented by the above formula (4-8) ispreferable. Such a polymer exhibits further smaller PEB temperaturedependence in ordinary lithography, and a more uniform resist patternsize can be obtained even on the surface of a large substrate with adiameter of 300 mm or greater.

Moreover, in this polymer also, the constitutional unit represented bythe above formula (2), the constitutional unit represented by the aboveformula (3-1-1), and the constitutional unit represented by the aboveformula (4-8), are not necessarily all the same, but may be a mixture oftwo or more kinds thereof, as long as they can be represented by generalformulas as described above. In addition, in this polymer, eachconstitutional unit may have any given sequence. Accordingly, thispolymer may be a random copolymer, an alternating copolymer, or a blockcopolymer.

In this case also, the total ratio of the constitutional unitrepresented by the above formula (2) in the polymer is preferablybetween 5% and 30% by mole. In addition, the total ratio of theconstitutional unit represented by the above formula (3-1-1) in thepolymer is preferably between 30% and 60% by mole. Moreover, the totalratio of the constitutional unit represented by the above formulas (4-8)in the polymer is preferably between 30% and 60% by mole. By adjustingthe ratios of constitutional units within the above ranges, much highereffects can be obtained from the present invention.

In this polymer, as a constitutional unit represented by the aboveformula (3-1-1), a constitutional unit derived from 2-loweralkyl-2-adamantyl (meth)acrylate such as 2-methyl-2-adamantyl(meth)acrylate or 2-ethyl-2-adamantyl (meth)acrylate is preferable.

Moreover, a polymer is allowed to contain a constitutional unit derivedfrom a chain transfer agent by using such a chain transfer agent duringpolymerization. When the resist polymer of the present inventioncontains a constitutional unit derived from a chain transfer agent, itmay have higher effects.

Specific examples of a chain transfer agent that is preferably usedherein may include 1-butanethiol, 1-octanethiol (n-octyl mercaptan),cyclohexanethiol, 2-butanethiol, 1-decanethiol, 1-tetradecanethiol,2-methyl-1-propanethiol, 2-mercaptoethanol, and 1-thioglycerol.

In this case, generally, the amount of a chain transfer agent that isused when the resist polymer of the present invention is produced ispreferably 0.001% or more by mole, more preferably 0.1% or more by mole,and particularly preferably 1% or more by mole, based on the totalamount of monomers used for polymerization. In addition, the amount of achain transfer agent that is used when the resist polymer of the presentinvention is produced is preferably 5% or less by mole, and morepreferably 2% or less by mole, based on the total amount of monomersused for polymerization.

The polymer of the present invention may be a random copolymer, analternating copolymer, or a block copolymer.

3. Method of Producing the Resist Polymer of the Present Invention

The resist polymer of the present invention is usually obtained bycopolymerization of a monomer composition comprising at least one(meth)acrylic acid ester derivative having a cyano group represented bythe above formula (5), at least one monomer having an acid-dissociablegroup, and at least one monomer having a lactone skeleton, in thepresence of a polymerization initiator. In such polymerization using apolymerization initiator, a radical form of the polymerization initiatoris first generated. Thereafter, using this radical form as an origin,chain polymerization of monomers progresses.

As a polymerization initiator used for the production of the resistpolymer of the present invention, an initiator that efficientlygenerates radicals as a result of heating is preferable. Examples ofsuch a polymerization initiator may include: azo compounds such as2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, or2,2′-azobis[2-(2-imidazolin-2-yl)propane]; and organic peroxides such as2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. When a resist polymer usedin ArF excimer laser (wavelength: 193 nm) lithography is produced, apolymerization initiator that does not have an aromatic ring in amolecular structure thereof is preferably used, in order to minimize thereduction of the light transmittance of the obtained resist polymer(transmittance of a light with a wavelength of 193 nm). Moreover, takinginto consideration the safety during the polymerization or the like, apolymerization initiator whose 10 hours half-life temperature is 60° C.or more is preferably used.

When the resist polymer of the present invention is produced, a chaintransfer agent may be used. Using such a chain transfer agent, theamount of a polymerization initiator can be decreased when a polymerwith a low molecular weight is produced. In addition, the molecularweight distribution of the obtained polymer can be reduced. Suchreduction of the molecular weight distribution is caused by a decreasein generation of a polymer with a high molecular weight. Thus, when theobtained polymer is used for resists, its solubility in a resist solventis further improved, and generation of microgels or defects ispreferably decreased.

Preferred examples of a chain transfer agent may include 1-butanethiol,2-butanethiol, 1-octanethiol, 1-decanethiol, 1-tetradecanethiol,cyclohexanethiol, 2-methyl-1-propanethiol, 2-mercaptoethanol, and1-thioglycerol.

During a polymerization reaction, a polymer having radicals at thegrowth termini thereof are generated. When a chain transfer agent isused, such a radical at this growth terminus take a hydrogen atomcontained in the chain transfer agent, and a polymer with inactivatedgrowth termini is thereby generated. On the other hand, the chaintransfer agent that has lost hydrogen atom becomes structure having aradical, namely, radical species. Starting from such a radical species,chain polymerization of monomers is carried out again. Accordingly, theobtained polymer has chain transfer residues at the termini thereof.When a resist polymer used in ArF excimer laser (wavelength: 193 nm)lithography is produced, in order to minimize the reduction of the lighttransmittance of the obtained resist polymer (transmittance of a lightwith a wavelength of 193 nm), a chain transfer agent that does not havean aromatic ring is preferably used.

The amount of a polymerization initiator used is not particularlylimited. In order to increase the yield of copolymers, the amount ispreferably 0.1% or more by mole based on the total amount of monomersused for copolymerization. In order to narrow the molecular weightdistribution of copolymers, the amount is preferably 30% or less by molebased on the total amount of monomers used for copolymerization.Moreover, the amount of a polymerization initiator used is morepreferably 0.3% or more by mole, and particularly preferably 1% or moreby mole, based on the total amount of monomers used forcopolymerization.

The amount of a chain transfer agent used is not particularly limited.In order to narrow the molecular weight distribution of copolymers, theamount is preferably 0.001% or more by mole, and more preferably 0.1% ormore by mole, based on the total amount of monomers used forcopolymerization. In order not to decrease resist performance such assensitivity, resolution, or adhesiveness to the metal surface or thelike, when the obtained copolymers are used as resist compositions, theabove amount is preferably 30% or less by mole based on the total amountof monomers used for copolymerization. Moreover, when the resist polymerof the present invention is produced, the amount of a chain transferagent used is more preferably 5% or less by mole, and particularlypreferably 2% or less by mole, based on the total amount of monomersused for copolymerization.

A method of producing the polymer of the present invention is notparticularly limited. The production of the polymer of the presentinvention is generally carried out by solution polymerization. Apolymerization method that is called “dropping polymerization,” whichcomprises addition of monomers dropwise to a polymerization reactor, ispreferable. Among others, it is preferable that the polymer of thepresent invention be produced by a polymerization method that is called“dropping polymerization,” which conducts polymerization while adding toa polymerization reactor monomers that will become constitutional unitsof a polymer of interest as a result of polymerization (which may beeither monomers alone, or a solution obtained by dissolving monomers inan organic solvent), since a polymer with narrow compositiondistribution and/or narrow molecular weight distribution can easily beobtained by the above method.

In such a dropping polymerization method, for example, an organicsolvent has previously been added to a polymerization reactor, it isthen heated to a predetermined polymerization temperature. Thereafter, amonomer solution obtained by dissolving monomers, a polymerizationinitiator, and as necessary a chain transfer agent, in an organicsolvent, is added dropwise to an organic solvent placed in thepolymerization reactor. Such monomers may be added without beingdissolved in an organic solvent. In such a case, a solution obtained bydissolving a polymerization initiator and as necessary a chain transferagent in monomers is added dropwise to the organic solvent. Otherwise,it is also possible to add monomers dropwise to the polymerizationreactor without previously adding an organic solvent to the reactor.

Monomers, a polymerization initiator, and a chain transfer agent may beadded dropwise, singly or in any given combination.

A polymerization temperature applied in the dropping polymerizationmethod is not particularly limited. In general, it is preferably between50° C. and 150° C.

As an organic solvent used in the dropping polymerization method, asolvent, which is capable of dissolving all of monomers used, apolymerization initiator used, the obtained polymer, and a chaintransfer agent if such a chain transfer agent is used, is preferablyused. Examples of such an organic solvent may include 1,4-dioxane,isopropyl alcohol, acetone, tetrahydrofuran (hereinafter referred to as“THF” at times), methyl ethyl ketone (hereinafter referred to as “MEK”at time), methyl isobutyl ketone (hereinafter referred to as “MIBK” attimes), γ-butyrolactone, propylene glycol monomethylether acetate(hereinafter referred to as “PGMEA” at times), and ethyl lactate.

The concentration of monomers contained in a monomer solution that is tobe added dropwise to an organic solvent is not particularly limited, butit is preferably within a range between 5% and 50% by mass.

The amount of organic solvent that is to be added to a polymerizationreactor is not particularly limited and may be determined asappropriate. Generally, it is used within a range between 30% and 700%by mass based on the total amount of monomers used for copolymerization.

A polymer solution produced by methods such as solution polymerizationis diluted with a good solvent such as 1,4-dioxane, acetone, THF, MEK,MIBK, γ-butyrolactone, PGMEA, or ethyl lactate, to an appropriateviscosity, as necessary. Thereafter, the resultant is added dropwise toa large amount of poor solvent such as methanol or water, so as toprecipitate a polymer. This process is generally called reprecipitation,and it is extremely effective for eliminating unreacted monomers or apolymerization initiator remaining in the polymerization solution. Ifthese unreacted products remained as are, they would affect resistperformance. Thus, it is preferable to eliminate as many unreactedproducts as possible. The reprecipitation process is unnecessary in somecases. Subsequently, the precipitate was collected by filtration, and itis then sufficiently dried, so as to obtain the polymer of the presentinvention. Otherwise, it is also possible to directly use wet powdersafter filtration without being dried.

Moreover, the produced copolymer solution may be used, directly, or as aresist composition after being diluted with an appropriate solvent. Inthis case, additives such as a preservative may be added as appropriate.

4. The Resist Composition of the Present Invention

The resist composition of the present invention is obtained bydissolving the above-described resist polymer of the present inventionin a solvent. In addition, the chemically amplified resist compositionof the present invention is obtained by dissolving the above-describedresist polymer of the present invention and a photoacid generator in asolvent. The resist polymer of the present invention may be used aloneor in combination. Moreover, it is possible to directly use this polymersolution for a resist composition, without separating polymers from thesolution, or it is also possible to dilute this polymer solution with anappropriate solvent, so as to use for a resist composition.

With regard to the resist composition of the present invention, asolvent in which the resist polymer of the present invention isdissolved is arbitrarily selected depending on purpose. Such selectionof a solvent, however, may be restricted by reasons other thansolubility of resin, such as uniformity of a film coated, appearance, orsafety.

Examples of such solvents may include: linear or branched ketones suchas methyl ethyl ketone, methyl isobutyl ketone, 2-pentanone, or2-hexanone; cyclic ketones such as cyclopentanone or cyclohexanone;propylene glycol monoalkyl ether acetates such as propylene glycolmonomethyl ether acetate or propylene glycol monoethyl ether acetate;ethylene glycol monoalkyl ether acetates such as ethylene glycolmonomethyl ether acetate or ethylene glycol monoethyl ether acetate;propylene glycol monoalkyl ethers such as propylene glycol monomethylether or propylene glycol monoethyl ether; ethylene glycol monoalkylethers such as ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, or ethylene glycol monoisopropyl ether; diethyleneglycol alkyl ethers such as diethylene glycol dimethyl ether, diethyleneglycol monomethyl ether, or diethylene glycol diethyl ether; esters suchas ethyl acetate or ethyl lactate; alcohols such as n-propyl alcohol,isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, cyclohexanol, or1-octanol; 1,4-dioxane, ethylene carbonate, and γ-butyrolactone. Thesesolvents may be used alone or in combination.

The content of a solvent is generally 200 parts or more by mass, andmore preferably 300 parts or more by mass, based on 100 parts by mass ofa resist polymer (the polymer of the present invention). In addition,the content of a solvent is generally 5,000 parts or less by mass, andmore preferably 2,000 parts or less by mass, based on 100 parts by massof a resist polymer (the polymer of the present invention).

When the resist polymer of the present invention is used for achemically amplified resist, it is necessary to use a photoacidgenerator.

A photoacid generator contained in the chemically amplified resistcomposition of the present invention may arbitrarily be selected fromthose that can be used as an acid generator for chemically amplifiedresist compositions. Such a photoacid generator may be used alone or incombination.

Examples of such a photoacid generator may include onium salt compounds,sulfone imide compounds, sulfone compounds, sulfonate compounds, quinonediazide compounds, and diazomethane compounds. Of these, onium saltcompounds such as a sulfonium salt, an iodonium salt, a phosphoniumsalt, a diazonium salt, and a pyridinium salt are preferable as aphotoacid generator. Specific examples of the onium salt compounds mayinclude triphenyl sulfonium triflate, triphenyl sulfoniumhexafluoroantimonate, triphenyl sulfonium naphthalenesulfonate,(hydroxyphenyl) benzylmethyl sulfonium toluenesulfonate, diphenyliodonium triflate, diphenyl iodonium pyrenesulfonate, diphenyl iodoniumdodecylbenzenesulfonate, diphenyl iodonium hexafluoroantimonate,p-methyl phenyl diphenyl sulfonium nonafluorobutanesulfonate, andtri(tert-butylphenyl) sulfonium trifluoromethanesulfonate.

The content of a photoacid generator is determined as appropriate,depending on the type of a photoacid generator selected. It is generally0.1 parts or more by mass, and more preferably 0.5 parts or more bymass, based on 100 parts by mass of a resist polymer (the polymer of thepresent invention). By setting the content of a photoacid generator inthe above range, a chemical reaction is sufficiently promoted by thecatalytic action of acid generated as a result of light exposure. Inaddition, the content of a photoacid generator is generally 20 parts orless by mass, and more preferably 10 parts or less by mass, based on 100parts by mass of a resist polymer (the polymer of the presentinvention). By setting the content of a photoacid generator in the aboverange, the stability of a resist composition is improved, and unevennessgenerated when the composition is applied, or scum or the like generatedin a developing process is significantly reduced.

Furthermore, a nitrogen-containing compound may be added to thechemically amplified resist composition of the present invention. Byadding such a nitrogen-containing compound into the chemically amplifiedresist composition of the present invention, a resist pattern shape orfilm-left stability over time is further improved. That is to say, thesectional shape of the resist pattern becomes almost rectangular.Further, after a resist film is exposed to a light and then heated(PEB), it may be left for several hours before the next developingprocess in the mass production line of semiconductors. In such a case,deterioration of the sectional shape of the resist pattern occurred whena resist film is left (over time) is suppressed by addition of anitrogen-containing compound.

All of known nitrogen-containing compounds can be used herein. Amongothers, amine is preferable, and a secondary lower aliphatic amine and atertiary lower aliphatic amine are more preferable.

The term “lower aliphatic amine” is used herein to mean alkylamine oralkyl alcohol amine having 5 or less carbon atoms.

Examples of such a secondary lower aliphatic amine or a tertiary loweraliphatic amine may include trimethylamine, diethylamine, triethylamine,di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, andtriethanolamine. Among others, a tertiary alkanolamine such astriethanolamine is more preferable as a nitrogen-containing compound.

A nitrogen-containing compound may be used alone or in combination.

The content of a nitrogen-containing compound is determined asappropriate, depending on the type of a nitrogen-containing compoundselected. In general, it is preferably 0.01 parts or more by mass basedon 100 parts by mass of a resist polymer (the polymer of the presentinvention). By setting the content of a nitrogen-containing compound inthe above range, the form of a resist pattern becomes more rectangular.In addition, in general, the content of a nitrogen-containing compoundis preferably 2 parts or less by mass based on 100 parts by mass of aresist polymer (the polymer of the present invention). By setting thecontent of a nitrogen-containing compound in the above range,deterioration in sensitivity can be reduced.

Furthermore, organic carboxylic acid, phosphorus oxo acid, or aderivative thereof may be added into the chemically amplified resistcomposition of the present invention. By adding these compounds into thechemically amplified resist composition of the present invention,deterioration in sensitivity caused by adding a nitrogen-containingcompound can be prevented, and further, the shape of a resist pattern,film-left stability over time, or the like are further improved.

Examples of organic carboxylic acids may include malonic acid, citricacid, malic acid, succinic acid, benzoic acid, and salicylic acid.

Examples of phosphorus oxo acids or derivatives thereof may include:phosphoric acids and derivatives thereof (esters thereof), such asphosphoric acid, phosphoric acid di-n-butyl ester and phosphoric aciddiphenyl ester; phosphonic acids and derivatives thereof (estersthereof), such as phosphonic acid, phosphonic acid dimethyl ester,phosphonic acid di-n-butyl ester, phenyl phosphonate, phosphonic aciddiphenyl ester and phosphonic acid dibenzyl ester; and phosphinic acidsand derivatives thereof (esters thereof), such as phosphinic acid andphenyl phosphinate. Of these, phosphonic acid is preferable.

These compounds (organic carboxylic acids, phosphorus oxo acids, orderivatives thereof) may be used alone or in combination.

The content of these compounds (organic carboxylic acids, phosphorus oxoacids, or derivatives thereof) is determined as appropriate, dependingon the type of a compound selected. In general, it is preferably 0.01parts or more by mass based on 100 parts by mass of a resist polymer(the polymer of the present invention). By setting the content of thesecompounds in the above range, the form of a resist pattern becomes morerectangular. In addition, in general, the content of these compounds(organic carboxylic acid, phosphorus oxo acid, or a derivative thereof)is preferably 5 parts or less by mass based on 100 parts by mass of aresist polymer (the polymer of the present invention). By setting thecontent of those compounds in the above range, reduction in the film ofa resist pattern can be prevented.

Both a nitrogen-containing compound, and organic carboxylic acid,phosphorus oxo acid or a derivative thereof, may be contained in thechemically amplified resist composition of the present invention.Alternatively, either one may be contained therein.

In addition, the chemically amplified resist composition of the presentinvention can further comprise various additives such as a surfactant,other quencher, sensitizer, antihalation agent, stabilizer andantifoaming agent, if necessary. The amount of these additives is notparticularly limited, but it may be determined as appropriate.

The resist polymer of the present invention may be used as a resistcomposition that is used for metal etching, photofabrication,plate-making, holograms, color filters, phase difference films, etc.

5. Pattern Formation Method of the Present Invention

Next, an example of the pattern formation method of the presentinvention will be explained.

First, the chemically amplified resist composition of the presentinvention is coated by spin-coating or the like on the surface of asubstrate such as a silicon wafer, on which a pattern is to be formed.Then, the substrate, on which the chemically amplified resistcomposition is coated, is dried by baking treatment (pre-bake), so thata resist film is formed on the substrate.

Next, a light with a wavelength of 250 nm or shorter is applied to thethus obtained resist film through a photomask (exposure). The light usedfor the exposure is preferably a KrF excimer laser, an ArF excimerlaser, or an F₂ excimer laser, and particularly preferably an ArFexcimer laser. Moreover, exposure with electron beam is also preferable.

After exposure, heat treatment (post exposure baking, PEB) is carriedout as appropriate. Thereafter, the substrate is immersed in an alkalinedeveloping solution, so as to eliminate the exposed portion bydissolving it therein (development). Any known alkaline developingsolution can be used herein. After the development, the substrate isrinsed with pure water or the like, as appropriate. Thus, a resistpattern is formed on the substrate to be processed.

In general, a substrate on which a resist pattern has been formed isappropriately subjected to heat treatment (postbaking) so that theresist is reinforced. Areas having no resists are selectively etched.After the etching, the resist is generally eliminated using a releasingagent.

EXAMPLES

The present invention will be explained more specifically in thefollowing examples. However, the examples are not intended to limit thescope of the invention. The term “part,” found in the following examplesand comparative examples, is used to mean “part by mass,” unlessotherwise specified.

Measurement of the physical properties of the produced polymers wascarried out by the following methods:

<Mass Average Molecular Weight of Resist Polymer>

Approximately 20 mg of a resist polymer was dissolved in 5 ml oftetrahydrofuran. The solution was then filtered through a 0.5-μmmembrane filter, so as to prepare a sample solution. The mass averagemolecular weight of this sample solution was measured using gelpermeation chromatography (GPC) manufactured by Tosoh Corp. For thismeasurement, 3 separation columns (Shodex GPC K-805L (product name)manufactured by Showa Denko K.K.) were used in series. Tetrahydrofuranwas used as a solvent, and polystyrene was used as a standard polymerunder conditions of a flow rate of 1.0 ml/min, using a differentialrefractometer as a detector, a measurement temperature of 40° C., and aninjection volume of 0.1 ml.

<Average Copolymerization Composition Ratio of Polymers Used for Resists(mol %)>

The average copolymerization composition ratio of polymers was obtainedby ¹H-NMR measurement. For this measurement, GSX-400 FT-NMR (productname) manufactured by JEOL was used. A solution containing approximately5% by mass of a resist polymer sample in chloroform deuteride, acetonedeuteride, or dimethyl sulfoxide deuteride was placed in a test tubewith a diameter of 5 mmφ. Thereafter, integration was carried out 64times under conditions of a measurement temperature of 40° C., anobservation frequency of 400 MHz, and a single pulse mode.

In addition, a resist composition was prepared using the producedpolymer by the following method, and the physical properties and thelike thereof were measured.

<Preparation of Resist Composition>

100 parts of the produced resist polymer, 2 parts of triphenyl sulfoniumtriflate used as a photoacid generator, and 700 parts of PGMEA used as asolvent were mixed, so as to form a homogeneous solution. The obtainedsolution was then filtered through a membrane filter with a pore size of0.1 μm, so as to prepare a resist composition solution.

<Formation of Resist Pattern>

The prepared resist composition solution was spin-coated on a siliconwafer, and pre-baking was carried out using a hot plate at 120° C. for60 seconds, so as to form a resist film having a film thickness of 0.4μm. Subsequently, the film was exposed using an ArF excimer laser lightexposure machine (wavelength: 193 nm), and then, post exposure bakingwas carried out using a hot plate at 120° C. for 60 seconds. Thereafter,development was carried out at room temperature using 2.38% by mass oftetramethylammonium hydroxide aqueous solution, followed by washing withpure water and drying, so as to form a resist pattern.

<Sensitivity>

Sensitivity was defined as a light exposure (mJ/cm²), at which a maskwith a line-and-space pattern of 0.16 μm is transcribed into a linewidth of 0.16 μm. Such a light exposure was measured as sensitivity.

<Resolution>

Resolution was defined as the minimal dimension (μm) of a resistpattern, which was imaged when exposure was carried out at theabove-described light exposure.

<Line Edge Roughness>

With regard to a 5-μm side portion in the longitudinal direction of a0.20-μm resist pattern obtained by the minimum light exposure in orderto reproduce 0.20-μm of a resist pattern on a mask, 50 points ofdistance from the standard line at which the pattern side portion shouldbe located were measured using JSM-6340F field emission-type scanningelectron microscope (product name) manufactured by JEOL. Then, astandard deviation was obtained, and 3σ was calculated. The smaller thisvalue, the better performance that can be achieved.

<Shape of Resist Pattern>

The vertical section of the aforementioned 0.20-μm resist pattern wasobserved with JSM-6340F field emission-type scanning electron microscope(product name) manufactured by JEOL. When the sectional shape wasrectangular, the evaluation is “O”, and when the sectional shape was aconvex or concave, the evaluation is “X”.

<Amount of Microgels>

With regard to the prepared resist composition solution, the number ofmicrogels in the solution immediately after preparation of the solution(microgel initial value) and the number of microgels in the solutionafter it had been left at 4° C. for 1 week (the number of microgelsafter a certain period of time) were measured using a particle countermanufactured by Rion Co., Ltd. Thereafter, the microgel initial valueand the number of microgels increased, which was calculated by anequation: (the number of microgels after a certain period of time)−(themicrogel initial value), were evaluated.

It is to be noted that the number of microgels with a particle size of0.25 μm or greater existing in 1 ml of the resist composition solutionwas measured herein.

Example 1

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 34.0 parts of propylene glycol monomethylethyl acetate (hereinafter referred to as PGMEA) were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 14.6parts of β-methacryloyloxy-γ-butyrolactone (hereinafter referred to asHGBMA), 22.5 parts of 2-methacryloyloxy-2-methyladamantane (hereinafterreferred to as MAdMA), 3.7 parts of 2- or 3-cyano-5-norbornylmethacrylate (hereinafter referred to as CNNMA), 61.2 parts of PGMEA,and 2.08 parts of dimethyl-2,2′-azobis isobutylate (hereinafter referredto as DAIB) was added dropwise to the flask using a dropping device at acertain rate over 6 hours, and the mixture was then retained at 80° C.for 1 hour. Thereafter, while stirring, the obtained reaction solutionwas added dropwise to approximately 30 times its volume of methanol, soas to obtain a white precipitate (copolymer A-1). In order to eliminateunreacted monomers remaining in the precipitate, the obtainedprecipitate was separated by filtration. The precipitate was then washedwith methanol the volume of which is approximately 30 times of themonomers used in the polymerization. Thereafter, the precipitate wasseparated by filtration, and the washed precipitate was then dried underreduced pressure at 50° C. for approximately 40 hours to obtaincopolymer A-1.

The physical properties of the obtained copolymer A-1 were measured. Theresults are shown in Table 1.

Example 2

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 37.9 parts of tetrahydrofuran (hereinafterreferred to as THF) were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 70° C. while stirring. Amonomer solution obtained by mixing 20.9 parts of 8- or9-acryloyloxy-4-oxatricyclo[5.2.1.0^(2,6)]-decan-3-one (hereinafterreferred to as OTDA), 18.8 parts of 2-methacryloyloxy-2-ethyladamantane(hereinafter referred to as EAdMA), 5.7 parts of 2- or3-cyano-5-norbornyl acrylate (hereinafter referred to as CNNA), 68.2parts of THF, 1.80 parts of 2,2′-azobisisobutyronitrile (hereinafterreferred to as AIBN), and 0.24 parts of 2-mercaptoethanol was addeddropwise to the flask using a dropping device at a certain rate over 6hours, and the mixture was then retained at 70° C. for 1 hour.Thereafter, while stirring, the obtained reaction solution was addeddropwise to approximately 30 times its volume of methanol, so as toobtain a white precipitate (copolymer A-2). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer A-2.

The physical properties of the obtained copolymer A-2 were measured. Theresults are shown in Table 1.

Example 3

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 22.4 parts of PGMEA and 9.7 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 21.5 parts of2-exo-methacryloyloxy-4,8-dioxatricyclo-[4.2.1.0^(3,7)]nonan-5-one(hereinafter referred to as ONLMA), 23.0 parts of4-methacryloyloxy-4-ethyl-tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodecane(hereinafter referred to as EDMA), 4.1 parts of CNNMA, 79.4 parts ofPGMEA, 34.0 parts of γ-butyrolactone, 0.70 parts of DAIB, and 0.58 partsof n-octylmercaptan was added dropwise to the flask using a droppingdevice at a certain rate over 6 hours, and the mixture was then retainedat 80° C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-3).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-3.

The physical properties of the obtained copolymer A-3 were measured. Theresults are shown in Table 1.

Example 4

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 30.8 parts of PGMEA and 3.4 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 12.6 parts ofα-methacryloyloxy-γ-butyrolactone (hereinafter referred to as GBLMA),21.1 parts of MAdMA, 7.0 parts of 1-cyano-2-cyclohexyl methacrylate(hereinafter referred to as CNCMA) represented by the following formula(20-12):

55.4 parts of PGMEA, 6.2 parts of γ-butyrolactone, and 1.64 parts ofAIBN was added dropwise to the flask using a dropping device at acertain rate over 6 hours, and the mixture was then retained at 80° C.for 1 hour. Thereafter, while stirring, the obtained reaction solutionwas added dropwise to approximately 30 times its volume of methanol, soas to obtain a white precipitate (copolymer A-4). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer A-4.

The physical properties of the obtained copolymer A-4 were measured. Theresults are shown in Table 1.

Example 5

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 30.8 parts of PGMEA and 3.4 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 12.6 parts of GBLMA, 21.1 parts ofMAdMA, 7.4 parts of CNNMA, 55.4 parts of PGMEA, 6.2 parts ofγ-butyrolactone, and 1.64 parts of AIBN was added dropwise to the flaskusing a dropping device at a certain rate over 6 hours, and the mixturewas then retained at 80° C. for 1 hour. Thereafter, while stirring, theobtained reaction solution was added dropwise to approximately 30 timesits volume of methanol, so as to obtain a white precipitate (copolymerA-5). Thereafter, the same operations as conducted in Example 1 werecarried out, so as to obtain a copolymer A-5.

The physical properties of the obtained copolymer A-5 were measured. Theresults are shown in Table 1.

Example 6

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 37.7 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 18.2parts of OTDA, 15.9 parts of MAdMA, 4.4 parts of1-acryloyloxy-3-hydroxyadamantane (hereinafter referred to as HAdA), 6.2parts of CNNMA, 67.9 parts of PGMEA, 1.64 parts of AIBN, and 0.58 partsof n-octylmercaptan was added dropwise to the flask using a droppingdevice at a certain rate over 6 hours, and the mixture was then retainedat 80° C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-6).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-6.

The physical properties of the obtained copolymer A-6 were measured. Theresults are shown in Table 1.

Example 7

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 28.2 parts of PGMEA and 7.1 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 12.2 parts of HGBMA, 22.3 parts ofEAdMA, 7.8 parts of CNNMA, 50.8 parts of PGMEA, 12.7 parts ofγ-butyrolactone, and 1.96 parts of AIBN was added dropwise to the flaskusing a dropping device at a certain rate over 6 hours, and the mixturewas then retained at 80° C. for 1 hour. Thereafter, while stirring, theobtained reaction solution was added dropwise to approximately 30 timesits volume of methanol, so as to obtain a white precipitate (copolymerA-7). Thereafter, the same operations as conducted in Example 1 werecarried out, so as to obtain a copolymer A-7.

The physical properties of the obtained copolymer A-7 were measured. Theresults are shown in Table 1.

Example 8

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 38.2 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 17.5parts of 8- or 9-methacryloyloxy-4-oxatricyclo[5.2.1.0^(2,6)]decan-3-one(hereinafter referred to as OTDMA), 20.6 parts of MAdMA, 7.8 parts ofCNNMA, 68.8 parts of PGMEA, 1.80 parts of AIBN, and 0.44 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-8).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-8.

The physical properties of the obtained copolymer A-8 were measured. Theresults are shown in Table 1.

Example 9

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 37.5 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 18.2parts of OTDA, 18.4 parts of EAdMA, 8.4 parts of CNNA, 67.4 parts ofPGMEA, 1.96 parts of AIBN, and 0.58 parts of n-octylmercaptan was addeddropwise to the flask using a dropping device at a certain rate over 6hours, and the mixture was then retained at 80° C. for 1 hour.Thereafter, while stirring, the obtained reaction solution was addeddropwise to approximately 30 times its volume of methanol, so as toobtain a white precipitate (copolymer A-9). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer A-9.

The physical properties of the obtained copolymer A-9 were measured. Theresults are shown in Table 1.

Example 10

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 37.7 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 18.2parts of OTDA, 16.9 parts of EAdMA, 4.4 parts of 1-methacryloyloxyadamantane (hereinafter referred to as AdMA), 5.7 parts of CNNA, 67.8parts of PGMEA, and 4.26 parts of AIBN was added dropwise to the flaskusing a dropping device at a certain rate over 6 hours, and the mixturewas then retained at 80° C. for 1 hour. Thereafter, while stirring, theobtained reaction solution was added dropwise to approximately 30 timesits volume of methanol, so as to obtain a white precipitate (copolymerA-10). Thereafter, the same operations as conducted in Example 1 werecarried out, so as to obtain a copolymer A-10.

The physical properties of the obtained copolymer A-10 were measured.The results are shown in Table 2.

Example 11

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 35.1 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 14.6parts of GBLMA, 22.5 parts of MAdMA, 5.0 parts of2,2,3,3-tetracyano-5-norbornyl methacrylate (hereinafter referred to asTCNMA), 63.2 parts of PGMEA, and 2.30 parts of DAIB was added dropwiseto the flask using a dropping device at a certain rate over 6 hours, andthe mixture was then retained at 80° C. for 1 hour. Thereafter, whilestirring, the obtained reaction solution was added dropwise toapproximately 30 times its volume of methanol, so as to obtain a whiteprecipitate (copolymer A-11). Thereafter, the same operations asconducted in Example 1 were carried out, so as to obtain a copolymerA-11.

The physical properties of the obtained copolymer A-11 were measured.The results are shown in Table 2.

Example 12

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 38.5 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 18.2parts of OTDA, 18.4 parts of EAdMA, 9.6 parts of 2- or3-cyano-5-methyl-5-norbornyl methacrylate (hereinafter referred to asCMNMA), 69.3 parts of PGMEA, 1.96 parts of AIBN, and 0.58 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-12).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-12.

The physical properties of the obtained copolymer A-12 were measured.The results are shown in Table 2.

Example 13

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 41.7 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 21.6parts of a mixture (hereinafter referred to as DOLMA) consisting of amonomer represented by formula (20-1) indicated below and a monomerrepresented by formula (20-2) indicated below:

20.6 parts of MAdMA, 7.8 parts of CNNMA, 75.0 parts of PGMEA, 1.32 partsof AIBN, and 0.44 parts of n-octylmercaptan was added dropwise to theflask using a dropping device at a certain rate over 6 hours, and themixture was then retained at 80° C. for 1 hour. Thereafter, whilestirring, the obtained reaction solution was added dropwise toapproximately 30 times its volume of methanol, so as to obtain a whiteprecipitate (copolymer A-13). Thereafter, the same operations asconducted in Example 1 were carried out, so as to obtain a copolymerA-13.

The physical properties of the obtained copolymer A-13 were measured.The results are shown in Table 2.

Example 14

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 31.6 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 9.1parts of 2-methylene-4,4-dimethyl-4-butanolide (hereinafter referred toas DMMB) represented by the following formula (20-3):

21.1 parts of MAdMA, 7.8 parts of CNNMA, 56.9 parts of PGMEA, 1.84 partsof DAIB, and 0.30 parts of n-octylmercaptan was added dropwise to theflask using a dropping device at a certain rate over 6 hours, and themixture was then retained at 80° C. for 1 hour. Thereafter, whilestirring, the obtained reaction solution was added dropwise toapproximately 30 times its volume of methanol, so as to obtain a whiteprecipitate (copolymer A-14). Thereafter, the same operations asconducted in Example 1 were carried out, so as to obtain a copolymerA-14.

The physical properties of the obtained copolymer A-14 were measured.The results are shown in Table 2.

Example 15

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 28.6 parts of PGMEA and 7.2 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 15.0 parts of a monomer representedby the following formula (20-4) (hereinafter referred to as BLEMA):

20.1 parts of MAdMA, 7.8 parts of CNNMA, 51.6 parts of PGMEA, 12.9 partsof γ-butyrolactone, 1.32 parts of AIBN, and 0.38 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-15).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-15.

The physical properties of the obtained copolymer A-15 were measured.The results are shown in Table 2.

Example 16

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 27.1 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 13.9parts of GBLMA, 12.8 parts of tert-butyl methacrylate (hereinafterreferred to as TBMA), 5.7 parts of CNNMA, 48.7 parts of PGMEA, 1.32parts of AIBN, and 0.18 parts of n-octylmercaptan was added dropwise tothe flask using a dropping device at a certain rate over 6 hours, andthe mixture was then retained at 80° C. for 1 hour. Thereafter, whilestirring, the obtained reaction solution was added dropwise toapproximately 30 times its volume of methanol, so as to obtain a whiteprecipitate (copolymer A-16). Thereafter, the same operations asconducted in Example 1 were carried out, so as to obtain a copolymerA-16.

The physical properties of the obtained copolymer A-16 were measured.The results are shown in Table 2.

Example 17

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 29.0 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80°C. while stirring. A monomer solution obtained by mixing 16.2parts of BLEMA, 12.8 parts of TBMA, 5.7 parts of CNNMA, 52.1 parts ofPGMEA, 1.32 parts of AIBN, and 0.14 parts of n-octylmercaptan was addeddropwise to the flask using a dropping device at a certain rate over 6hours, and the mixture was then retained at 80° C. for 1 hour.Thereafter, while stirring, the obtained reaction solution was addeddropwise to approximately 30 times its volume of methanol, so as toobtain a white precipitate (copolymer A-17). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer A-17.

The physical properties of the obtained copolymer A-17 were measured.The results are shown in Table 2.

Example 18

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 40.0 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 19.2parts of a monomer represented by the following formula (20-5)(hereinafter referred to as MOTDMA):

20.6 parts of MAdMA, 8.2 parts of CNNMA, 71.9 parts of PGMEA, 1.32 partsof AIBN, and 0.26 parts of n-octylmercaptan was added dropwise to theflask using a dropping device at a certain rate over 6 hours, and themixture was then retained at 80° C. for 1 hour. Thereafter, whilestirring, the obtained reaction solution was added dropwise toapproximately 30 times its volume of methanol, so as to obtain a whiteprecipitate (copolymer A-18). Thereafter, the same operations asconducted in Example 1 were carried out, so as to obtain a copolymerA-18.

The physical properties of the obtained copolymer A-18 were measured.The results are shown in Table 2.

Example 19

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 27.1 parts of PGMEA and 11.6 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 18.4 parts of OTDMA, 19.2 parts ofMAdMA, 4.1 parts of CNNMA, 4.7 parts of HAdMA, 48.7 parts of PGMEA, 20.9parts of γ-butyrolactone, 0.98 parts of AIBN, and 0.62 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-19).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-19.

The physical properties of the obtained copolymer A-19 were measured.The results are shown in Table 3.

Example 20

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 32.8 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 18.3parts of a monomer represented by the following formula (20-6)(hereinafter referred to as MCLMA):

11.6 parts of TBMA, 9.4 parts of CNNMA, 59.0 parts of PGMEA, 1.14 partsof AIBN, and 0.26 parts of n-octylmercaptan was added dropwise to theflask using a dropping device at a certain rate over 6 hours, and themixture was then retained at 80° C. for 1 hour. Thereafter, whilestirring, the obtained reaction solution was added dropwise toapproximately 30 times its volume of methanol, so as to obtain a whiteprecipitate (copolymer A-20). Thereafter, the same operations asconducted in Example 1 were carried out, so as to obtain a copolymerA-20.

The physical properties of the obtained copolymer A-20 were measured.The results are shown in Table 3.

Example 21

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 39.1 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 14.6parts of OTDMA, 23.4 parts of MAdMA, 8.9 parts of a monomer representedby the following formula (20-7) (hereinafter referred to as MCCMA):

70.4 parts of PGMEA, 1.32 parts of AIBN, and 0.36 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-21).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-21.

The physical properties of the obtained copolymer A-21 were measured.The results are shown in Table 3.

Example 22

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 35.2 parts of PGMEA and 8.8 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 23.5 parts of a mixture consistingof a monomer represented by formula (20-8) indicated below and a monomerrepresented by formula (20-9) indicated below (hereinafter referred toas DOLAMA):

21.5 parts of MAdMA, 7.8 parts of CNNMA, 63.4 parts of PGMEA, 15.9 partsof γ-butyrolactone, 1.32 parts of AIBN, and 0.50 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-22).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-22.

The physical properties of the obtained copolymer A-22 were measured.The results are shown in Table 3.

Example 23

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 26.1 parts of PGMEA and 11.2 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 17.3 parts of2-exo-methacryloyloxy-4-oxatricyclo-[4.2.1.0^(3,7)]nonan-5-one(hereinafter referred to as OTNMA), 19.2 parts of MAdMA, 8.2 parts ofCNNMA, 46.9 parts of PGMEA, 20.1 parts of γ-butyrolactone, 1.48 parts ofAIBN, and 0.58 parts of n-octylmercaptan was added dropwise to the flaskusing a dropping device at a certain rate over 6 hours, and the mixturewas then retained at 80° C. for 1 hour. Thereafter, while stirring, theobtained reaction solution was added dropwise to approximately 30 timesits volume of methanol, so as to obtain a white precipitate (copolymerA-23). Thereafter, the same operations as conducted in Example 1 werecarried out, so as to obtain a copolymer A-23.

The physical properties of the obtained copolymer A-23 were measured.The results are shown in Table 3.

Example 24

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 27.0 parts of PGMEA and 6.8 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 13.6 parts of GBLMA, 18.7 parts ofMAdMA, 8.2 parts of CNNMA, 48.6 parts of PGMEA, 12.2 parts ofγ-butyrolactone, 1.32 parts of AIBN, and 1.02 parts of n-octylmercaptanwas added dropwise to the flask using a dropping device at a certainrate over 6 hours, and the mixture was then retained at 80° C. for 1hour. Thereafter, while stirring, the obtained reaction solution wasadded dropwise to approximately 30 times its volume of methanol, so asto obtain a white precipitate (copolymer A-24). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer A-24.

The physical properties of the obtained copolymer A-24 were measured.The results are shown in Table 3.

Example 25

A copolymer A-25 was obtained in the same manner as in Example 24 withthe exception that the amount of n-octylmercaptan in the monomersolution was set at 0.58 parts.

The physical properties of the obtained copolymer A-25 were measured.The results are shown in Table 3.

Example 26

A copolymer A-26 was obtained in the same manner as in Example 24 withthe exception that the amount of n-octylmercaptan in the monomersolution was set at 0.38 parts.

The physical properties of the obtained copolymer A-26 were measured.The results are shown in Table 3.

Example 27

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 39.1 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 14.6parts of OTDMA, 23.4 parts of MAdMA, 9.4 parts of a monomer representedby the following formula (20-13) (hereinafter referred to as CNNAMA):

70.4 parts of PGMEA, 1.32 parts of AIBN, and 0.36 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer A-27).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer A-27.

The physical properties of the obtained copolymer A-27 were measured.The results are shown in Table 3.

Comparative Example 1

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 34.0 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 16.0parts of HGBMA, 24.8 parts of MAdMA, 61.2 parts of PGMEA, and 2.08 partsof DAIB was added dropwise to the flask using a dropping device at acertain rate over 6 hours, and the mixture was then retained at 80° C.for 1 hour. Thereafter, while stirring, the obtained reaction solutionwas added dropwise to approximately 30 times its volume of methanol, soas to obtain a white precipitate (copolymer B-1). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer B-1.

The physical properties of the obtained copolymer B-1 were measured. Theresults are shown in Table 4.

Comparative Example 2

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 22.8 parts of PGMEA and 9.8 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 20.2 parts of ONLMA, 19.7 parts ofEDMA, 9.0 parts of 1-methacryloyloxy-3-hydroxyadamantane (hereinafterreferred to as HAdMA), 79.8 parts of PGMEA, 34.2 parts ofγ-butyrolactone, 0.70 parts of DAIB, and 0.58 parts of n-octylmercaptanwas added dropwise to the flask using a dropping device at a certainrate over 6 hours, and the mixture was then retained at 80° C. for 1hour. Thereafter, while stirring, the obtained reaction solution wasadded dropwise to approximately 30 times its volume of methanol, so asto obtain a white precipitate (copolymer B-2). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer B-2.

The physical properties of the obtained copolymer B-2 were measured. Theresults are shown in Table 4.

Comparative Example 3

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 35.0 parts of PGMEA and 10.9 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 24.9 parts of OTNMA, 21.8 parts ofEAdMA, 63.0 parts of PGMEA, 7.0 parts of γ-butyrolactone, and 3.94 partsof AIBN was added dropwise to the flask using a dropping device at acertain rate over 6 hours, and the mixture was then retained at 80° C.for 1 hour. Thereafter, while stirring, the obtained reaction solutionwas added dropwise to approximately 30 times its volume of methanol, soas to obtain a white precipitate (copolymer B-3). Thereafter, the sameoperations as conducted in Example 1 were carried out, so as to obtain acopolymer B-3.

The physical properties of the obtained copolymer B-3 were measured. Theresults are shown in Table 4.

Comparative Example 4

A total amount of a monomer solution obtained by mixing 8.9 parts of2′-acetoxyethyl methacrylate (hereinafter referred to as AEMA), 9.0parts of 1-butyl methacrylate (hereinafter referred to as BMA), 14.0parts of CNNMA, 4.45 parts of methacrylic acid (hereinafter referred toas MM), 109.2 parts of isopropanol, 1.96 parts of AIBN, and 0.58 partsof n-octylmercaptan, were placed in a flask equipped with a nitrogeninlet, a stirrer, a condenser and a thermometer on a water bath, under anitrogen atmosphere. Thereafter, while stirring, the temperature of thewater bath was increased to 60° C. Thereafter, the mixture was retainedat 60° C. for 5.5 hours for polymerization. Subsequently, whilestirring, the obtained reaction solution was added dropwise to 6 L ofhexane, so as to obtain a white precipitate (copolymer B-4). In order toeliminate a monomer portion remaining in the precipitate, the obtainedprecipitate was filtered off, and the obtained filtrate was then washedwith 300 ml of hexane 5 times. Thereafter, the precipitate was filteredoff, and the obtained filtrate was dried at approximately 40° C. under areduced pressure for approximately 40 hours.

The physical properties of the obtained copolymer B-4 were measured. Theresults are shown in Table 4.

Comparative Example 5

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 36.6 parts of PGMEA were placed under anitrogen atmosphere, and the temperature of the water bath was increasedto 80° C. while stirring. A monomer solution obtained by mixing 15.5parts of a monomer represented by the following formula (20-10)(hereinafter referred to as CLMA):

20.6 parts of MAdMA, 7.8 parts of CNNMA, 65.9 parts of PGMEA, 1.80 partsof AIBN, and 0.44 parts of n-octylmercaptan was added dropwise to theflask using a dropping device at a certain rate over 6 hours, and themixture was then retained at 80° C. for 1 hour. Thereafter, whilestirring, the obtained reaction solution was added dropwise toapproximately 30 times its volume of methanol, so as to obtain a whiteprecipitate (copolymer B-5). Thereafter, the same operations asconducted in Example 1 were carried out, so as to obtain a copolymerB-5.

The physical properties of the obtained copolymer B-5 were measured. Theresults are shown in Table 4.

Reference Example 1

In a flask equipped with a nitrogen inlet, a stirrer, a condenser and athermometer on a water bath, 26.4 parts of PGMEA and 11.3 parts ofγ-butyrolactone were placed under a nitrogen atmosphere, and thetemperature of the water bath was increased to 80° C. while stirring. Amonomer solution obtained by mixing 17.3 parts of OTNMA, 19.2 parts ofMAdMA, 4.1 parts of CNNMA, 4.7 parts of HAdMA, 47.6 parts of PGMEA, 20.4parts of γ-butyrolactone, 0.98 parts of AIBN, and 0.62 parts ofn-octylmercaptan was added dropwise to the flask using a dropping deviceat a certain rate over 6 hours, and the mixture was then retained at 80°C. for 1 hour. Thereafter, while stirring, the obtained reactionsolution was added dropwise to approximately 30 times its volume ofmethanol, so as to obtain a white precipitate (copolymer B-6).Thereafter, the same operations as conducted in Example 1 were carriedout, so as to obtain a copolymer B-6.

The physical properties of the obtained copolymer B-6 were measured. Theresults are shown in Table 4.

Reference Example 2

A copolymer B-7 was obtained in the same manner as in Example 23 withthe exception that the amount of n-octylmercaptan in the monomersolution was set at 0.14 parts.

The physical properties of the obtained copolymer B-7 were measured. Theresults are shown in Table 4.

TABLE 1 Example 1 2 3 4 5 6 7 8 9 Copolymer A-1 A-2 A-3 A-4 A-5 A-6 A-7A-8 A-9 Mass average molecular 12,500 10,500 11,000 10,000 12,000 10,0009,500 9,500 8,500 weight (Mw) Molecular weight 1.75 1.60 1.62 1.75 1.681.59 1.69 1.66 1.62 distribution (Mw/Mn) Composition CNNMA 10 10 20 1520 20 ratio of CNNA 15 20 monomer units TCNMA in polymer CMNMA (mol %)MCCMA CNCMA 20 MAdMA 45 40 40 35 40 EAdMA 40 40 40 EDMA 40 TBMA AEMAHAdMA HAdA 10 AdMA HGBMA 45 40 GBLMA 40 40 BLEMA OTNMA CLMA OTDMA 40OTDA 45 40 40 ONLMA 50 DOLMA DOLAMA MOTDMA MCLMA DMMB BMA MAASensitivity (mJ/cm²) 6.4 7.4 8.1 7.1 7.6 6.8 5.8 7.3 7.0 Resolution (μm)0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 0.13 Line edge roughness(nm) 9 510 8 9 8 4 5 5 Resist pattern shape ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Number of Initial 5  8  6 <5 <5  6 <5 <5 <5 Microgels Increased <5 <5 <5 <5 <5 <5 <5 <5<5 (the number)

TABLE 2 Example 10 11 12 13 14 15 16 17 18 Copolymer A-10 A-11 A-12 A-13A-14 A-15 A-16 A-17 A-18 Mass average molecular 9,000 10,500 9,50010,000 9,500 8,000 11,500 12,000 9,000 weight (Mw) Molecular weight 1.791.60 1.69 1.65 1.62 1.42 1.49 1.52 1.60 distribution (Mw/Mn) CompositionCNNMA 20 20 20 15 15 20 ratio of CNNA 15 monomer units TCNMA 10 inpolymer CMNMA 20 (mol %) MCCMA CNCMA MAdMA 45 40 40 40 40 EAdMA 35 40EDMA TBMA 40 40 AEMA HAdMA HAdA AdMA 10 HGBMA GBLMA 45 45 BLEMA 40 45OTNMA CLMA OTDMA OTDA 40 40 ONLMA DOLMA 40 DOLAMA MOTDMA 40 MCLMA DMMB40 BMA MAA Sensitivity (mJ/cm²) 7.1 6.9 7.2 6.9 7.2 6.7 7.0 6.8 7.3Resolution (μm) 0.13 0.13 0.13 0.13 0.14 0.13 0.15 0.15 0.13 Line edgeroughness(nm) 6 6 7 6 7 8 9 7 6 Resist pattern shape ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯Number of Initial <5 <5 <5 <5 <5 <5 <5 <5 <5 Microgels Increased <5 <5<5 <5 <5 <5 <5 <5 <5 (the number)

TABLE 3 Example 19 20 21 22 23 24 25 26 27 Copolymer A-19 A-20 A-21 A-22A-23 A-24 A-25 A-26 A-27 Mass average molecular 10,000 11,000 8,0009,500 7,500 5,200 6,700 7,800 8,400 weight (Mw) Molecular weight 1.691.55 1.52 1.66 1.67 1.42 1.52 1.58 1.56 distribution (Mw/Mn) CompositionCNNMA 10 25 20 20 22 22 22 ratio of CNNA monomer units TCNMA in polymerCMNMA (mol %) MCCMA 20 CNCMA CNNAMA 20 MAdMA 40 45 45 40 39 39 39 40EAdMA EDMA TBMA 35 AEMA HAdMA 10 HAdA AdMA HGBMA GBLMA 39 39 39 40 BLEMAOTNMA 40 CLMA OTDMA 40 35 OTDA ONLMA DOLMA DOLAMA 35 MOTDMA MCLMA 40DMMB BMA MAA Sensitivity (mJ/cm²) 7.5 7.4 6.9 7.2 6.9 6.9 7.0 7.3 7.1Resolution (μm) 0.13 0.15 0.13 0.13 0.13 0.12 0.12 0.12 0.13 Line edgeroughness(nm) 6 6 4 6 7 7 8 8 8 Resist pattern shape ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯Number of Initial <5 <5 <5 <5  6 <5 <5 <5 <5 Microgels Increased <5 <5<5 <5 <5 <5 <5 <5 <5 (the number)

TABLE 4 Comparative Example Reference Example 1 2 3 4 5 1 2 CopolymerB-1 B-2 B-3 B-4 B-5 B-6 B-7 Mass average molecular 11,500 10,500 8,50017,500 10,000 10,000 12,000 weight (Mw) Molecular weight 1.86 1.64 1.781.89 1.63 1.72 1.78 distribution (Mw/Mn) Composition CNNMA 29 20 10 20ratio of CNNA monomer units TCNMA in polymer CMNMA (mol %) MCCMA CNCMAMAdMA 50 40 40 40 EAdMA 40 EDMA 40 TBMA AEMA 22 HAdMA 15 10 HAdA AdMAHGBMA 50 GBLMA BLEMA OTNMA 60 40 40 CLMA 40 OTDMA OTDA ONLMA 45 DOLMADOLAMA MOTDMA MCLMA DMMB BMA 27 MAA 22 Sensitivity (mJ/cm²) 5.9 8.4 6.86.5 7.3 7.5 8.4 Resolution (μm) 0.13 0.14 0.14 0.16 0.13 0.15 0.15 Lineedge roughness(nm) 29 10 34 42 5 10 12 Resist pattern shape ◯ X X X X X◯ Number of Initial 14 9 12 10 <5 9 8 Microgels Increased 20 8 340 11  6260 94 (the number)

The resist compositions, for which the polymers used for resists of thepresent invention (Examples 1 to 27) were used, had sufficientsensitivity and resolution, as well as excellent resist pattern. Theseresist compositions are also excellent in terms of line edge roughness,having a small degree of generation of microgels in a resist solution.

In contrast, the resist composition, for which the polymer ofComparative Example 1 containing no constitutional units having a cyanogroup was used, was inferior in terms of line edge roughness. Inaddition, a large degree of generation of microgels in the resistsolution was observed.

The resist composition, for which the polymer of Comparative Example 2containing no constitutional units having a cyano group was used, wasinferior in terms of resist pattern shape.

The resist composition, for which the polymer of Comparative Example 3containing no constitutional units having a cyano group was used, wasinferior in terms of resist pattern shape and line edge roughness. Inaddition, a large degree of generation of microgels in the resistsolution was observed.

The resist composition, for which the polymer of Comparative Example 4containing no constitutional units having a lactone skeleton was used,was inferior in terms of resist pattern shape and line edge roughness.

The resist composition, for which the polymer of Comparative Example 5containing a constitutional unit having a lactone skeleton that wasdifferent from the constitutional unit of the resist polymer of thepresent invention was used, was inferior in terms of resist patternshape.

When Example 19 was compared with Reference Example 1 including adifferent constitutional unit having a lactone skeleton, the resistcomposition, for which the polymer obtained in Example 19 was used, wassuperior in terms of resist pattern shape. In addition, a small degreeof generation of microgels was confirmed in the resist solution.

Moreover, when Example 23 was compared with Reference Example 2 of whichthe mass average molecular weight is different, in the case of theresist composition, for which the polymer obtained in Example 23 wasused, a small degree of generation of microgels was confirmed in theresist solution.

Example 28

100 parts of the resist polymer obtained in Example 24 (copolymer A-24),2 parts of p-methylphenyldiphenylsulfonium nonafluorobutanesulfonateused as a photoacid generator, 0.8 parts oftri(tert-butylphenyl)sulfonium trifluoromethanesulfonate, and 0.25 partsof triethanolamine used as a nitrogen-containing compound, weredissolved in 25 parts of γ-butyrolactone and 900 parts of a mixtureconsisting of propylene glycol monomethyl ether acetate and ethyllactate (mass ratio: 8:2), so as to prepare a positive type resistcomposition solution.

Subsequently, an organic antireflection coating composition(manufactured by Brewer Science; product name: “ARC-29A”) was appliedonto a silicon wafer (diameter: 200 mm) using a spinner. It was thenburned on a hot plate at 215° C. for 60 seconds and dried, so as to forman organic antireflection coating film having a film thickness of 77 nm.

The prepared solution of the positive resist composition was applied onthe organic antireflection coating film using a spinner. It was thenprebaked on a hot plate at 125° C. for 90 seconds and dried, so as toform a resist film having a film thickness of 250 nm. Subsequently,using an ArF exposure device (manufactured by Nikon Corp.; NSR-S302; NA(numerical aperture)=0.60, ⅔ annular), an ArF excimer laser (wavelength:193 nm) was applied to the resist film via a mask pattern (binary).Thereafter, post exposure baking (PEB) was carried out at 125° C. for 90seconds using a hot plate. Thereafter, puddle development was carriedout at 23° C. for 30 seconds using 2.38% by mass of atetramethylammonium hydroxide aqueous solution, and the resultant wasthen washed with pure water for 20 seconds. It was then dried, so as toform a resist pattern.

When the obtained 130-nm mask was exposed to a light with a lightexposure (30 mJ/cm²) necessary for transcription of the above mask into130 nm, the resolving power of the line-and-space pattern and that ofthe trench pattern were 121 nm and 127 nm, respectively. Thus, bothpatterns have good shapes.

Moreover, the maximum and minimum sizes of the trench pattern formed ona wafer were measured. As a result, the sizes were found to be 128 nmand 125 nm, respectively. Thus, a difference between the values wasextremely small.

A resist pattern (trench pattern) was formed in the same above mannerwith the exception that the PEB temperature was changed from 125° C. to120° C. or to 130° C. The average size of the resist patterns formed ateach PEB temperature was measured, and the amount of resist pattern sizechanged per unit temperature was then calculated from the above averagesize. As a result, it was found to be extremely small (1.0 nm/° C.).

Example 29

A resist pattern was formed in the same manner as in Example 28 with theexception that the resist polymer obtained in Example 25 (copolymerA-25) was used instead of the resist polymer obtained in Example 24(copolymer A-24).

When the obtained 130-nm mask was exposed to a light with a lightexposure (30 mJ/cm²) necessary for transcription of the above mask into130 nm, the resolving power of the line-and-space pattern and that ofthe trench pattern were 119 nm and 130 nm, respectively. Thus, bothpatterns have good forms.

Moreover, the maximum and minimum sizes of the trench pattern formed ona wafer were measured. As a result, the sizes were found to be 128 nmand 131 nm, respectively. Thus, a difference between the values wasextremely small.

A resist pattern (trench pattern) was formed in the same above mannerwith the exception that the PEB temperature was changed from 125° C. to120° C. or to 130° C. The average size of the resist patterns formed ateach PEB temperature was measured, and the amount of resist pattern sizechanged per unit temperature was then calculated from the above averagesize. As a result, it was found to be extremely small (1.5 nm/° C.).

Example 30

A resist pattern was formed in the same manner as in Example 28 with theexception that the resist polymer obtained in Example 26 (copolymerA-26) was used instead of the resist polymer obtained in Example 24(copolymer A-24).

When the obtained 130-nm mask was exposed to a light with a lightexposure (30 mJ/cm²) necessary for transcription of the above mask into130 nm, the resolving power of the line-and-space pattern and that ofthe trench pattern were 123 nm and 130 nm, respectively. Thus, bothpatterns have good forms.

Moreover, the maximum and minimum sizes of the trench pattern formed ona wafer were measured. As a result, the sizes were found to be 131 nmand 128 nm, respectively. Thus, a difference between the values wasextremely small.

A resist pattern (trench pattern) was formed in the same above mannerwith the exception that the PEB temperature was changed from 125° C. to120° C. or to 130° C. The average size of the resist patterns formed ateach PEB temperature was measured, and the amount of resist pattern sizechanged per unit temperature was then calculated from the above averagesize. As a result, it was found to be extremely small (1.8 nm/° C.).

The resist compositions (Examples 28 to 30), for which the resistpolymers of the present invention were used, had sufficient sensitivityand resolution, and was excellent in terms of the shape of the formedresist pattern and the uniformity of the formed resist pattern in thewafer surface, having a small degree of PEB temperature dependence. Theaforementioned excellent results were obtained on a substrate with adiameter of 200 mm. Accordingly, the resist compositions (Examples 28 to30), for which the resist polymers of the present invention were used,can achieve a sufficiently uniform resist pattern size in plane even ona larger substrate with a diameter of 300 mm or greater, for example.

Comparative Example 6

A resist pattern was formed in the same manner as in Example 28 with theexceptions that a copolymer (mass average molecular weight (Mw): 8,800;and molecular weight distribution (Mw/Mn): 1.79) represented by formula(20-11) indicated below was used instead of the resist polymer obtainedin Example 24 (copolymer A-24), and that the PEB temperature was changedfrom 125° C. to 130° C.

(wherein, in formula (20-11), n:m:I=40 mol %:40 mol %:20 mol %).

When the obtained 130-nm mask was exposed to a light with a lightexposure (22 mJ/cm²) necessary for transcription of the above mask into130 nm, the resolving power of the line-and-space pattern and that ofthe trench pattern were 126 nm and 130 nm, respectively. Thus, bothpatterns have good forms. However, the sizes of resist patterns formedon a wafer varied more widely than those in Examples 28 to 30. Thus, theuniformity in the wafer surface was deteriorated.

A resist pattern (trench pattern) was formed in the same above mannerwith the exception that the PEB temperature was changed from 130° C. to135° C. The average size of the resist patterns formed at the above PEBtemperatures was obtained, and the amount of resist pattern size changedper unit temperature was then obtained from the above average size. As aresult, it was found to be larger (5.2 nm/° C.) than those in Examples28 to 30.

INDUSTRIAL APPLICABILITY

A resist composition, for which the resist polymer of the presentinvention is used, has high sensitivity and high resolution, andprovides a good resist pattern shape, having a small degree ofoccurrence of line edge roughness and a small degree of generation ofmicrogels. Thus, a high-precision fine resist pattern can stably beformed with the polymer of the present invention. Accordingly, a resistcomposition, for which the resist polymer of the present invention isused, can preferably be used in DUV excimer laser lithography orelectron beam lithography, and particularly preferably in lithographyusing an ArF excimer laser (wavelength: 193 nm).

Moreover, a resist composition, for which the resist polymer of thepresent invention is used, can achieve a uniform resist pattern size inplane on a large substrate having a diameter of 300 mm or greater, forexample, and the thus formed resist pattern has a small degree of PEBtemperature dependence.

1. A resist polymer, which comprises a constitutional unit representedby formula (1-1) indicated below, a constitutional unit having anacid-dissociable group, and a constitutional unit having a lactoneskeleton that is represented by at least one selected from the groupconsisting of formulas (4-1), (4-2), (4-3), (4-5), (4-6), and (4-10)indicated below:

wherein, in formula (1-1), R⁰¹ represents a hydrogen atom or a methylgroup; R⁰³ represents a hydrogen atom or a linear or branched alkylgroup having 1 to 6 carbon atoms; and each of A⁰¹ and A⁰² independentlyrepresents a hydrogen atom, or a linear or branched alkyl group having 1to 4 carbon atoms, or A⁰¹ and A⁰² together represent —O—, —S—, —NH—, oran alkylene chain having 1 to 6 carbon atoms,

wherein, in formula (4-1), R⁴¹ represents a hydrogen atom or a methylgroup; each of R⁴⁰¹ and R⁴⁰² independently represents a hydrogen atom, alinear or branched alkyl group having 1 to 6 carbon atoms, a hydroxygroup, a carboxy group, or a carboxy group that is esterified withalcohol having 1 to 6 carbon atoms, or R⁴⁰¹ and R⁴⁰² together represent—O—, —S—, —NH—, or a —(CH₂)_(j)— chain wherein j represents an integerbetween 1 and 6; i represents 0 or 1; X⁵ represents a linear or branchedalkyl group having 1 to 6 carbon atoms that may have, as a substituent,at least one selected from the group consisting of a hydroxy group, acarboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy grouphaving 1 to 6 carbon atoms, a carboxy group that is esterified withalcohol having 1 to 6 carbon atoms, a cyano group, and an amino group, ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, or an aminogroup; and n5 represents an integer between 0 and 4, and m represents 1or 2, provided that when n5 is 2 or greater, X⁵ may be a plurality ofdifferent groups, wherein, in formula (4-2), R⁴² represents a hydrogenatom or a methyl group; each of R²⁰¹ and R²⁰² independently represents ahydrogen atom, a linear or branched alkyl group having 1 to 6 carbonatoms, a hydroxy group, a carboxy group, or a carboxy group esterifiedwith alcohol having 1 to 6 carbon atoms; A¹ and A² together represent—O—, —S—, —NH—, a —(CH₂)_(k)— chain wherein k represents an integerbetween 1 and 6; X⁶ represents a linear or branched alkyl group having 1to 6 carbon atoms that may have, as a substituent, at least one selectedfrom the group consisting of a hydroxy group, a carboxy group, an acylgroup having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbonatoms, a carboxy group that is esterified with alcohol having 1 to 6carbon atoms, a cyano group, and an amino group, a hydroxy group, acarboxy group, an acyl group having 1 to 6 carbon atoms, an alkoxy grouphaving 1 to 6 carbon atoms, a carboxy group that is esterified withalcohol having 1 to 6 carbon atoms, or an amino group; and n6 representsan integer between 0 and 4, provided that when n6 is 2 or greater, X⁶may be a plurality of different groups, wherein, in formula (4-3), R⁴³represents a hydrogen atom or a methyl group; each of R²⁰³ and R²⁰⁴independently represents a hydrogen atom, a linear or branched alkylgroup having 1 to 6 carbon atoms, a hydroxy group, a carboxy group, or acarboxy group esterified with alcohol having 1 to 6 carbon atoms; eachof A³ and A⁴ independently represents a hydrogen atom, a linear orbranched alkyl group having 1 to 6 carbon atoms, a hydroxy group, acarboxy group, or a carboxy group that is esterified with alcohol having1 to 6 carbon atoms, or A³ and A⁴ together represent —O—, —S—, —NH—, ora —(CH₂)₁— chain wherein 1 represents an integer between 1 and 6; X⁷represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, acyano group, and an amino group, a hydroxy group, a carboxy group, anacyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6carbon atoms, a carboxy group that is esterified with alcohol having 1to 6 carbon atoms, or an amino group; and n7 represents an integerbetween 0 and 4, provided that when n7 is 2 or greater, X⁷ may be aplurality of different groups, wherein, in formula (4-5), R⁴⁵ representsa hydrogen atom or a methyl group; each of R⁸ and R⁹ independentlyrepresents a hydrogen atom or a linear or branched alkyl group having 1to 8 carbon atoms; each of R⁵², R⁶², and R⁷² independently represents ahydrogen atom or a methyl group; each of Y¹², Y²², and Y³² independentlyrepresents —CH₂— or —CO—O—, and at least one of them represents —CO—O—;X⁹ represents a linear or branched alkyl group having 1 to 6 carbonatoms that may have, as a substituent, at least one selected from thegroup consisting of a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, a cyano group, and an amino group, a hydroxy group, a carboxygroup, an acyl group having 1 to 6 carbon atoms, an alkoxy group having1 to 6 carbon atoms, a carboxy group that is esterified with alcoholhaving 1 to 6 carbon atoms, or an amino group; and n9 represents aninteger between 0 and 4, provided that when n9 is 2 or greater, X⁹ maybe a plurality of different groups, wherein, in formula (4-6), R⁴⁶represents a hydrogen atom or a methyl group; R¹⁰ represents a hydrogenatom or a linear or branched alkyl group having 1 to 8 carbon atoms;each of R⁵³, R⁶³, and R⁷³ independently represents a hydrogen atom or amethyl group; each of Y¹³, Y²³, and Y³³ independently represents —CH₂—or —CO—O—, and at least one of them represents —CO—O—; X¹⁰ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, a cyano group,and an amino group, a hydroxy group, a carboxy group, an acyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,a carboxy group that is esterified with alcohol having 1 to 6 carbonatoms, or an amino group; and n10 represents an integer between 0 and 4,provided that when n10 is 2 or greater, X¹⁰ may be a plurality ofdifferent groups, and wherein, in formula (4-10), each of R⁹¹, R⁹², R⁹³,and R⁹⁴ independently represents a hydrogen atom, a linear or branchedalkyl group having 1 to 6 carbon atoms, a hydroxy group, a carboxygroup, or a carboxy group that is esterified with alcohol having 1 to 6carbon atoms, or R⁹¹ and R⁹² together represent —O—, —S—, —NH—, or a—(CH₂)_(t)— chain wherein t represents an integer between 1 and 6; andm1 represents 1 or
 2. 2. The resist polymer according to claim 1, whichcomprises at least one constitutional unit represented by said formula(1-1), at least one constitutional unit selected from the groupconsisting of those represented by formulas (3-1-1), (3-3-1), and (3-5)indicated below:

wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups, and wherein,in formula (3-3-1), R³³ represents a hydrogen atom or a methyl group; R⁴represents an alkyl group having 1 to 3 carbon atoms; X³ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup, a hydroxy group, a carboxy group, an acyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups; and

wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup, and at least one constitutional unit represented by the followingformula (4-7):

wherein, in formula (4-7), R⁴⁷ represents a hydrogen atom or a methylgroup.
 3. The resist polymer according to claim 2, wherein the totalratio of at least one constitutional unit represented by said formula(1-1) is between 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by said formulas (3-1-1), (3-3-1), and (3-5) is between 30%and 60% by mole, and the total ratio of the constitutional unitrepresented by said formula (4-7) is between 30% and 60% by mole.
 4. Theresist polymer according to claim 1, which comprises at least oneconstitutional unit represented by said formula (1-1), at least oneconstitutional unit selected from the group consisting of thoserepresented by formulas (3-1-1), (3-3-1), and (3-5) indicated below:

wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups, and wherein,in formula (3-3-1), R³³ represents a hydrogen atom or a methyl group; R⁴represents an alkyl group having 1 to 3 carbon atoms; X³ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup, a hydroxy group, a carboxy group, an acyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups; and

wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup, and at least one constitutional unit represented by the followingformula (4-8):

wherein, in formula (4-8), R⁴⁸ represents a hydrogen atom or a methylgroup.
 5. The resist polymer according to claim 4, wherein the totalratio of at least one constitutional unit represented by said formula(1-1) is between 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by said formulas (3-1-1), (3-3-1), and (3-5) is between 30%and 60% by mole, and the total ratio of the constitutional unitrepresented by said formula (4-8) is between 30% and 60% by mole.
 6. Theresist polymer according to claim 1, which comprises at least oneconstitutional unit represented by said formula (1-1), at least oneconstitutional unit selected from the group consisting of thoserepresented by formulas (3-1-1), (3-3-1), and (3-5) indicated below:

wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups, and wherein,in formula (3-3-1), R³³ represents a hydrogen atom or a methyl group; R⁴represents an alkyl group having 1 to 3 carbon atoms; X³ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup, a hydroxy group, a carboxy group, an acyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups; and

wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup, and at least one constitutional unit represented by the followingformula (4-11):

wherein, in formula (4-11), R⁴¹¹ represents a hydrogen atom or a methylgroup.
 7. The resist polymer according to claim 6, wherein the totalratio of at least one constitutional unit represented by said formula(1-1) is between 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by said formulas (3-1-1), (3-3-1), and (3-5) is between 30%and 60% by mole, and the total ratio of the constitutional unitrepresented by said formula (4-11) is between 30% and 60% by mole. 8.The resist polymer according to claim 1, which comprises at least oneconstitutional unit represented by said formula (1-1), at least oneconstitutional unit selected from the group consisting of thoserepresented by formulas (3-1-1), (3-3-1), and (3-5) indicated below:

wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups, and wherein,in formula (3-3-1), R³³ represents a hydrogen atom or a methyl group; R⁴represents an alkyl group having 1 to 3 carbon atoms; X³ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup, a hydroxy group, a carboxy group, an acyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups; and

wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup, and at least one constitutional unit represented by the followingformula (4-9):

wherein, in formula (4-9), R⁴⁹ represents a hydrogen atom or a methylgroup.
 9. The resist polymer according to claim 8, wherein the totalratio of at least one constitutional unit represented by said formula(1-1) is between 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by said formulas (3-1-1), (3-3-1), and (3-5) is between 30%and 60% by mole, and the total ratio of the constitutional unitrepresented by said formula (4-9) is between 30% and 60% by mole. 10.The resist polymer according to claim 1, which comprises at least oneconstitutional unit represented by said formula (1-1), at least oneconstitutional unit selected from the group consisting of thoserepresented by formulas (3-1-1), (3-3-1), and (3-5) indicated below:

wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups, and wherein,in formula (3-3-1), R³³ represents a hydrogen atom or a methyl group; R⁴represents an alkyl group having 1 to 3 carbon atoms; X³ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup, a hydroxy group, a carboxy group, an acyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups; and

wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup, and at least one constitutional unit selected from the groupconsisting of those represented by said formulas (4-2) and (4-3). 11.The resist polymer according to claim 10, wherein the total ratio of atleast one constitutional unit represented by said formula (1-1) isbetween 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by said formulas (3-1-1), (3-3-1), and (3-5) is between 30%and 60% by mole, and the total ratio of at least one constitutional unitselected from the group consisting of those represented by said formulas(4-2) and (4-3) is between 30% and 60% by mole.
 12. A resist polymer,which comprises a constitutional unit represented by formula (2)indicated below:

wherein, in formula (2), R⁰¹ represents a hydrogen atom or a methylgroup, at least one constitutional unit having an acid-dissociable groupselected from the group consisting of those represented by formulas(3-1-1), (3-3-1), and (3-5) indicated below:

wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups, and wherein,in formula (3-3-1), R³³ represents a hydrogen atom or a methyl group; R⁴represents an alkyl group having 1 to 3 carbon atoms; X³ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup, a hydroxy group, a carboxy group, an acyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups; and

wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup, and at least one constitutional unit represented by the followingformula (4-11):

wherein, in formula (4-11), R⁴¹¹ represents a hydrogen atom or a methylgroup.
 13. The resist polymer according to claim 12, wherein the totalratio of at least one constitutional unit represented by said formula(2) is between 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by said formulas (3-1-1), (3-3-1), and (3-5) is between 30%and 60% by mole, and the total ratio of the constitutional unitrepresented by said formula (4-11) is between 30% and 60% by mole.
 14. Aresist polymer, which comprises a constitutional unit represented byformula (2) indicated below:

wherein, in formula (2), R⁰¹ represents a hydrogen atom or a methylgroup, at least one constitutional unit having an acid-dissociable groupselected from the group consisting of those represented by formulas(3-1-1), (3-3-1), and (3-5) indicated below:

wherein, in formula (3-1-1), R³¹ represents a hydrogen atom or a methylgroup; R¹ represents an alkyl group having 1 to 3 carbon atoms; X¹represents a linear or branched alkyl group having 1 to 6 carbon atomsthat may have, as a substituent, at least one selected from the groupconsisting of a hydroxy group, a carboxy group, an acyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, and anamino group, a hydroxy group, a carboxy group, an acyl group having 1 to6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n1 represents an integer between 0 and 4, and when n1is 2 or greater, X¹ may be a plurality of different groups, and wherein,in formula (3-3-1), R³³ represents a hydrogen atom or a methyl group; R⁴represents an alkyl group having 1 to 3 carbon atoms; X³ represents alinear or branched alkyl group having 1 to 6 carbon atoms that may have,as a substituent, at least one selected from the group consisting of ahydroxy group, a carboxy group, an acyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a carboxy group thatis esterified with alcohol having 1 to 6 carbon atoms, and an aminogroup, a hydroxy group, a carboxy group, an acyl group having 1 to 6carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a carboxygroup that is esterified with alcohol having 1 to 6 carbon atoms, or anamino group; and n3 represents an integer between 0 and 4, and qrepresents 0 or 1, provided that when n3 is 2 or greater, X³ may be aplurality of different groups; and

wherein, in formula (3-5), R³⁵ represents a hydrogen atom or a methylgroup, and at least one constitutional unit represented by the followingformula (4-9):

wherein, in formula (4-9), R⁴⁹ represents a hydrogen atom or a methylgroup.
 15. The resist polymer according to claim 14, wherein the totalratio of at least one constitutional unit represented by said formula(2) is between 5% and 30% by mole, the total ratio of at least oneconstitutional unit selected from the group consisting of thoserepresented by said formulas (3-1-1), (3-3-1), and (3-5) is between 30%and 60% by mole, and the total ratio of the constitutional unitrepresented by said formula (4-9) is between 30% and 60% by mole.